Fixed import error after last commit.v1.1.2-beta.8

27 files changed, 9368 insertions, 0 deletions

diff --git a/libs/aniso8601/__init__.py b/libs/aniso8601/__init__.py
new file mode 100644
index 000000000..033d30b9d
--- /dev/null
+++ b/libs/aniso8601/__init__.py
@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+from aniso8601.date import get_date_resolution, parse_date
+from aniso8601.duration import get_duration_resolution, parse_duration
+from aniso8601.interval import (
+    get_interval_resolution,
+    get_repeating_interval_resolution,
+    parse_interval,
+    parse_repeating_interval,
+)
+
+# Import the main parsing functions so they are readily available
+from aniso8601.time import (
+    get_datetime_resolution,
+    get_time_resolution,
+    parse_datetime,
+    parse_time,
+)
+
+__version__ = "9.0.1"
diff --git a/libs/aniso8601/builders/__init__.py b/libs/aniso8601/builders/__init__.py
new file mode 100644
index 000000000..834c72a6b
--- /dev/null
+++ b/libs/aniso8601/builders/__init__.py
@@ -0,0 +1,614 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import calendar
+from collections import namedtuple
+
+from aniso8601.exceptions import (
+    DayOutOfBoundsError,
+    HoursOutOfBoundsError,
+    ISOFormatError,
+    LeapSecondError,
+    MidnightBoundsError,
+    MinutesOutOfBoundsError,
+    MonthOutOfBoundsError,
+    SecondsOutOfBoundsError,
+    WeekOutOfBoundsError,
+    YearOutOfBoundsError,
+)
+
+DateTuple = namedtuple("Date", ["YYYY", "MM", "DD", "Www", "D", "DDD"])
+TimeTuple = namedtuple("Time", ["hh", "mm", "ss", "tz"])
+DatetimeTuple = namedtuple("Datetime", ["date", "time"])
+DurationTuple = namedtuple(
+    "Duration", ["PnY", "PnM", "PnW", "PnD", "TnH", "TnM", "TnS"]
+)
+IntervalTuple = namedtuple("Interval", ["start", "end", "duration"])
+RepeatingIntervalTuple = namedtuple("RepeatingInterval", ["R", "Rnn", "interval"])
+TimezoneTuple = namedtuple("Timezone", ["negative", "Z", "hh", "mm", "name"])
+
+Limit = namedtuple(
+    "Limit",
+    [
+        "casterrorstring",
+        "min",
+        "max",
+        "rangeexception",
+        "rangeerrorstring",
+        "rangefunc",
+    ],
+)
+
+
+def cast(
+    value,
+    castfunction,
+    caughtexceptions=(ValueError,),
+    thrownexception=ISOFormatError,
+    thrownmessage=None,
+):
+    try:
+        result = castfunction(value)
+    except caughtexceptions:
+        raise thrownexception(thrownmessage)
+
+    return result
+
+
+def range_check(valuestr, limit):
+    # Returns cast value if in range, raises defined exceptions on failure
+    if valuestr is None:
+        return None
+
+    if "." in valuestr:
+        castfunc = float
+    else:
+        castfunc = int
+
+    value = cast(valuestr, castfunc, thrownmessage=limit.casterrorstring)
+
+    if limit.min is not None and value < limit.min:
+        raise limit.rangeexception(limit.rangeerrorstring)
+
+    if limit.max is not None and value > limit.max:
+        raise limit.rangeexception(limit.rangeerrorstring)
+
+    return value
+
+
+class BaseTimeBuilder(object):
+    # Limit tuple format cast function, cast error string,
+    # lower limit, upper limit, limit error string
+    DATE_YYYY_LIMIT = Limit(
+        "Invalid year string.",
+        0000,
+        9999,
+        YearOutOfBoundsError,
+        "Year must be between 1..9999.",
+        range_check,
+    )
+    DATE_MM_LIMIT = Limit(
+        "Invalid month string.",
+        1,
+        12,
+        MonthOutOfBoundsError,
+        "Month must be between 1..12.",
+        range_check,
+    )
+    DATE_DD_LIMIT = Limit(
+        "Invalid day string.",
+        1,
+        31,
+        DayOutOfBoundsError,
+        "Day must be between 1..31.",
+        range_check,
+    )
+    DATE_WWW_LIMIT = Limit(
+        "Invalid week string.",
+        1,
+        53,
+        WeekOutOfBoundsError,
+        "Week number must be between 1..53.",
+        range_check,
+    )
+    DATE_D_LIMIT = Limit(
+        "Invalid weekday string.",
+        1,
+        7,
+        DayOutOfBoundsError,
+        "Weekday number must be between 1..7.",
+        range_check,
+    )
+    DATE_DDD_LIMIT = Limit(
+        "Invalid ordinal day string.",
+        1,
+        366,
+        DayOutOfBoundsError,
+        "Ordinal day must be between 1..366.",
+        range_check,
+    )
+    TIME_HH_LIMIT = Limit(
+        "Invalid hour string.",
+        0,
+        24,
+        HoursOutOfBoundsError,
+        "Hour must be between 0..24 with " "24 representing midnight.",
+        range_check,
+    )
+    TIME_MM_LIMIT = Limit(
+        "Invalid minute string.",
+        0,
+        59,
+        MinutesOutOfBoundsError,
+        "Minute must be between 0..59.",
+        range_check,
+    )
+    TIME_SS_LIMIT = Limit(
+        "Invalid second string.",
+        0,
+        60,
+        SecondsOutOfBoundsError,
+        "Second must be between 0..60 with " "60 representing a leap second.",
+        range_check,
+    )
+    TZ_HH_LIMIT = Limit(
+        "Invalid timezone hour string.",
+        0,
+        23,
+        HoursOutOfBoundsError,
+        "Hour must be between 0..23.",
+        range_check,
+    )
+    TZ_MM_LIMIT = Limit(
+        "Invalid timezone minute string.",
+        0,
+        59,
+        MinutesOutOfBoundsError,
+        "Minute must be between 0..59.",
+        range_check,
+    )
+    DURATION_PNY_LIMIT = Limit(
+        "Invalid year duration string.",
+        0,
+        None,
+        ISOFormatError,
+        "Duration years component must be positive.",
+        range_check,
+    )
+    DURATION_PNM_LIMIT = Limit(
+        "Invalid month duration string.",
+        0,
+        None,
+        ISOFormatError,
+        "Duration months component must be positive.",
+        range_check,
+    )
+    DURATION_PNW_LIMIT = Limit(
+        "Invalid week duration string.",
+        0,
+        None,
+        ISOFormatError,
+        "Duration weeks component must be positive.",
+        range_check,
+    )
+    DURATION_PND_LIMIT = Limit(
+        "Invalid day duration string.",
+        0,
+        None,
+        ISOFormatError,
+        "Duration days component must be positive.",
+        range_check,
+    )
+    DURATION_TNH_LIMIT = Limit(
+        "Invalid hour duration string.",
+        0,
+        None,
+        ISOFormatError,
+        "Duration hours component must be positive.",
+        range_check,
+    )
+    DURATION_TNM_LIMIT = Limit(
+        "Invalid minute duration string.",
+        0,
+        None,
+        ISOFormatError,
+        "Duration minutes component must be positive.",
+        range_check,
+    )
+    DURATION_TNS_LIMIT = Limit(
+        "Invalid second duration string.",
+        0,
+        None,
+        ISOFormatError,
+        "Duration seconds component must be positive.",
+        range_check,
+    )
+    INTERVAL_RNN_LIMIT = Limit(
+        "Invalid duration repetition string.",
+        0,
+        None,
+        ISOFormatError,
+        "Duration repetition count must be positive.",
+        range_check,
+    )
+
+    DATE_RANGE_DICT = {
+        "YYYY": DATE_YYYY_LIMIT,
+        "MM": DATE_MM_LIMIT,
+        "DD": DATE_DD_LIMIT,
+        "Www": DATE_WWW_LIMIT,
+        "D": DATE_D_LIMIT,
+        "DDD": DATE_DDD_LIMIT,
+    }
+
+    TIME_RANGE_DICT = {"hh": TIME_HH_LIMIT, "mm": TIME_MM_LIMIT, "ss": TIME_SS_LIMIT}
+
+    DURATION_RANGE_DICT = {
+        "PnY": DURATION_PNY_LIMIT,
+        "PnM": DURATION_PNM_LIMIT,
+        "PnW": DURATION_PNW_LIMIT,
+        "PnD": DURATION_PND_LIMIT,
+        "TnH": DURATION_TNH_LIMIT,
+        "TnM": DURATION_TNM_LIMIT,
+        "TnS": DURATION_TNS_LIMIT,
+    }
+
+    REPEATING_INTERVAL_RANGE_DICT = {"Rnn": INTERVAL_RNN_LIMIT}
+
+    TIMEZONE_RANGE_DICT = {"hh": TZ_HH_LIMIT, "mm": TZ_MM_LIMIT}
+
+    LEAP_SECONDS_SUPPORTED = False
+
+    @classmethod
+    def build_date(cls, YYYY=None, MM=None, DD=None, Www=None, D=None, DDD=None):
+        raise NotImplementedError
+
+    @classmethod
+    def build_time(cls, hh=None, mm=None, ss=None, tz=None):
+        raise NotImplementedError
+
+    @classmethod
+    def build_datetime(cls, date, time):
+        raise NotImplementedError
+
+    @classmethod
+    def build_duration(
+        cls, PnY=None, PnM=None, PnW=None, PnD=None, TnH=None, TnM=None, TnS=None
+    ):
+        raise NotImplementedError
+
+    @classmethod
+    def build_interval(cls, start=None, end=None, duration=None):
+        # start, end, and duration are all tuples
+        raise NotImplementedError
+
+    @classmethod
+    def build_repeating_interval(cls, R=None, Rnn=None, interval=None):
+        # interval is a tuple
+        raise NotImplementedError
+
+    @classmethod
+    def build_timezone(cls, negative=None, Z=None, hh=None, mm=None, name=""):
+        raise NotImplementedError
+
+    @classmethod
+    def range_check_date(
+        cls, YYYY=None, MM=None, DD=None, Www=None, D=None, DDD=None, rangedict=None
+    ):
+        if rangedict is None:
+            rangedict = cls.DATE_RANGE_DICT
+
+        if "YYYY" in rangedict:
+            YYYY = rangedict["YYYY"].rangefunc(YYYY, rangedict["YYYY"])
+
+        if "MM" in rangedict:
+            MM = rangedict["MM"].rangefunc(MM, rangedict["MM"])
+
+        if "DD" in rangedict:
+            DD = rangedict["DD"].rangefunc(DD, rangedict["DD"])
+
+        if "Www" in rangedict:
+            Www = rangedict["Www"].rangefunc(Www, rangedict["Www"])
+
+        if "D" in rangedict:
+            D = rangedict["D"].rangefunc(D, rangedict["D"])
+
+        if "DDD" in rangedict:
+            DDD = rangedict["DDD"].rangefunc(DDD, rangedict["DDD"])
+
+        if DD is not None:
+            # Check calendar
+            if DD > calendar.monthrange(YYYY, MM)[1]:
+                raise DayOutOfBoundsError(
+                    "{0} is out of range for {1}-{2}".format(DD, YYYY, MM)
+                )
+
+        if DDD is not None:
+            if calendar.isleap(YYYY) is False and DDD == 366:
+                raise DayOutOfBoundsError(
+                    "{0} is only valid for leap year.".format(DDD)
+                )
+
+        return (YYYY, MM, DD, Www, D, DDD)
+
+    @classmethod
+    def range_check_time(cls, hh=None, mm=None, ss=None, tz=None, rangedict=None):
+        # Used for midnight and leap second handling
+        midnight = False  # Handle hh = '24' specially
+
+        if rangedict is None:
+            rangedict = cls.TIME_RANGE_DICT
+
+        if "hh" in rangedict:
+            try:
+                hh = rangedict["hh"].rangefunc(hh, rangedict["hh"])
+            except HoursOutOfBoundsError as e:
+                if float(hh) > 24 and float(hh) < 25:
+                    raise MidnightBoundsError("Hour 24 may only represent midnight.")
+
+                raise e
+
+        if "mm" in rangedict:
+            mm = rangedict["mm"].rangefunc(mm, rangedict["mm"])
+
+        if "ss" in rangedict:
+            ss = rangedict["ss"].rangefunc(ss, rangedict["ss"])
+
+        if hh is not None and hh == 24:
+            midnight = True
+
+        # Handle midnight range
+        if midnight is True and (
+            (mm is not None and mm != 0) or (ss is not None and ss != 0)
+        ):
+            raise MidnightBoundsError("Hour 24 may only represent midnight.")
+
+        if cls.LEAP_SECONDS_SUPPORTED is True:
+            if hh != 23 and mm != 59 and ss == 60:
+                raise cls.TIME_SS_LIMIT.rangeexception(
+                    cls.TIME_SS_LIMIT.rangeerrorstring
+                )
+        else:
+            if hh == 23 and mm == 59 and ss == 60:
+                # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+                raise LeapSecondError("Leap seconds are not supported.")
+
+            if ss == 60:
+                raise cls.TIME_SS_LIMIT.rangeexception(
+                    cls.TIME_SS_LIMIT.rangeerrorstring
+                )
+
+        return (hh, mm, ss, tz)
+
+    @classmethod
+    def range_check_duration(
+        cls,
+        PnY=None,
+        PnM=None,
+        PnW=None,
+        PnD=None,
+        TnH=None,
+        TnM=None,
+        TnS=None,
+        rangedict=None,
+    ):
+        if rangedict is None:
+            rangedict = cls.DURATION_RANGE_DICT
+
+        if "PnY" in rangedict:
+            PnY = rangedict["PnY"].rangefunc(PnY, rangedict["PnY"])
+
+        if "PnM" in rangedict:
+            PnM = rangedict["PnM"].rangefunc(PnM, rangedict["PnM"])
+
+        if "PnW" in rangedict:
+            PnW = rangedict["PnW"].rangefunc(PnW, rangedict["PnW"])
+
+        if "PnD" in rangedict:
+            PnD = rangedict["PnD"].rangefunc(PnD, rangedict["PnD"])
+
+        if "TnH" in rangedict:
+            TnH = rangedict["TnH"].rangefunc(TnH, rangedict["TnH"])
+
+        if "TnM" in rangedict:
+            TnM = rangedict["TnM"].rangefunc(TnM, rangedict["TnM"])
+
+        if "TnS" in rangedict:
+            TnS = rangedict["TnS"].rangefunc(TnS, rangedict["TnS"])
+
+        return (PnY, PnM, PnW, PnD, TnH, TnM, TnS)
+
+    @classmethod
+    def range_check_repeating_interval(
+        cls, R=None, Rnn=None, interval=None, rangedict=None
+    ):
+        if rangedict is None:
+            rangedict = cls.REPEATING_INTERVAL_RANGE_DICT
+
+        if "Rnn" in rangedict:
+            Rnn = rangedict["Rnn"].rangefunc(Rnn, rangedict["Rnn"])
+
+        return (R, Rnn, interval)
+
+    @classmethod
+    def range_check_timezone(
+        cls, negative=None, Z=None, hh=None, mm=None, name="", rangedict=None
+    ):
+        if rangedict is None:
+            rangedict = cls.TIMEZONE_RANGE_DICT
+
+        if "hh" in rangedict:
+            hh = rangedict["hh"].rangefunc(hh, rangedict["hh"])
+
+        if "mm" in rangedict:
+            mm = rangedict["mm"].rangefunc(mm, rangedict["mm"])
+
+        return (negative, Z, hh, mm, name)
+
+    @classmethod
+    def _build_object(cls, parsetuple):
+        # Given a TupleBuilder tuple, build the correct object
+        if type(parsetuple) is DateTuple:
+            return cls.build_date(
+                YYYY=parsetuple.YYYY,
+                MM=parsetuple.MM,
+                DD=parsetuple.DD,
+                Www=parsetuple.Www,
+                D=parsetuple.D,
+                DDD=parsetuple.DDD,
+            )
+
+        if type(parsetuple) is TimeTuple:
+            return cls.build_time(
+                hh=parsetuple.hh, mm=parsetuple.mm, ss=parsetuple.ss, tz=parsetuple.tz
+            )
+
+        if type(parsetuple) is DatetimeTuple:
+            return cls.build_datetime(parsetuple.date, parsetuple.time)
+
+        if type(parsetuple) is DurationTuple:
+            return cls.build_duration(
+                PnY=parsetuple.PnY,
+                PnM=parsetuple.PnM,
+                PnW=parsetuple.PnW,
+                PnD=parsetuple.PnD,
+                TnH=parsetuple.TnH,
+                TnM=parsetuple.TnM,
+                TnS=parsetuple.TnS,
+            )
+
+        if type(parsetuple) is IntervalTuple:
+            return cls.build_interval(
+                start=parsetuple.start, end=parsetuple.end, duration=parsetuple.duration
+            )
+
+        if type(parsetuple) is RepeatingIntervalTuple:
+            return cls.build_repeating_interval(
+                R=parsetuple.R, Rnn=parsetuple.Rnn, interval=parsetuple.interval
+            )
+
+        return cls.build_timezone(
+            negative=parsetuple.negative,
+            Z=parsetuple.Z,
+            hh=parsetuple.hh,
+            mm=parsetuple.mm,
+            name=parsetuple.name,
+        )
+
+    @classmethod
+    def _is_interval_end_concise(cls, endtuple):
+        if type(endtuple) is TimeTuple:
+            return True
+
+        if type(endtuple) is DatetimeTuple:
+            enddatetuple = endtuple.date
+        else:
+            enddatetuple = endtuple
+
+        if enddatetuple.YYYY is None:
+            return True
+
+        return False
+
+    @classmethod
+    def _combine_concise_interval_tuples(cls, starttuple, conciseendtuple):
+        starttimetuple = None
+        startdatetuple = None
+
+        endtimetuple = None
+        enddatetuple = None
+
+        if type(starttuple) is DateTuple:
+            startdatetuple = starttuple
+        else:
+            # Start is a datetime
+            starttimetuple = starttuple.time
+            startdatetuple = starttuple.date
+
+        if type(conciseendtuple) is DateTuple:
+            enddatetuple = conciseendtuple
+        elif type(conciseendtuple) is DatetimeTuple:
+            enddatetuple = conciseendtuple.date
+            endtimetuple = conciseendtuple.time
+        else:
+            # Time
+            endtimetuple = conciseendtuple
+
+        if enddatetuple is not None:
+            if enddatetuple.YYYY is None and enddatetuple.MM is None:
+                newenddatetuple = DateTuple(
+                    YYYY=startdatetuple.YYYY,
+                    MM=startdatetuple.MM,
+                    DD=enddatetuple.DD,
+                    Www=enddatetuple.Www,
+                    D=enddatetuple.D,
+                    DDD=enddatetuple.DDD,
+                )
+            else:
+                newenddatetuple = DateTuple(
+                    YYYY=startdatetuple.YYYY,
+                    MM=enddatetuple.MM,
+                    DD=enddatetuple.DD,
+                    Www=enddatetuple.Www,
+                    D=enddatetuple.D,
+                    DDD=enddatetuple.DDD,
+                )
+
+        if (starttimetuple is not None and starttimetuple.tz is not None) and (
+            endtimetuple is not None and endtimetuple.tz != starttimetuple.tz
+        ):
+            # Copy the timezone across
+            endtimetuple = TimeTuple(
+                hh=endtimetuple.hh,
+                mm=endtimetuple.mm,
+                ss=endtimetuple.ss,
+                tz=starttimetuple.tz,
+            )
+
+        if enddatetuple is not None and endtimetuple is None:
+            return newenddatetuple
+
+        if enddatetuple is not None and endtimetuple is not None:
+            return TupleBuilder.build_datetime(newenddatetuple, endtimetuple)
+
+        return TupleBuilder.build_datetime(startdatetuple, endtimetuple)
+
+
+class TupleBuilder(BaseTimeBuilder):
+    # Builder used to return the arguments as a tuple, cleans up some parse methods
+    @classmethod
+    def build_date(cls, YYYY=None, MM=None, DD=None, Www=None, D=None, DDD=None):
+
+        return DateTuple(YYYY, MM, DD, Www, D, DDD)
+
+    @classmethod
+    def build_time(cls, hh=None, mm=None, ss=None, tz=None):
+        return TimeTuple(hh, mm, ss, tz)
+
+    @classmethod
+    def build_datetime(cls, date, time):
+        return DatetimeTuple(date, time)
+
+    @classmethod
+    def build_duration(
+        cls, PnY=None, PnM=None, PnW=None, PnD=None, TnH=None, TnM=None, TnS=None
+    ):
+
+        return DurationTuple(PnY, PnM, PnW, PnD, TnH, TnM, TnS)
+
+    @classmethod
+    def build_interval(cls, start=None, end=None, duration=None):
+        return IntervalTuple(start, end, duration)
+
+    @classmethod
+    def build_repeating_interval(cls, R=None, Rnn=None, interval=None):
+        return RepeatingIntervalTuple(R, Rnn, interval)
+
+    @classmethod
+    def build_timezone(cls, negative=None, Z=None, hh=None, mm=None, name=""):
+        return TimezoneTuple(negative, Z, hh, mm, name)
diff --git a/libs/aniso8601/builders/python.py b/libs/aniso8601/builders/python.py
new file mode 100644
index 000000000..8956740e7
--- /dev/null
+++ b/libs/aniso8601/builders/python.py
@@ -0,0 +1,705 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import datetime
+from collections import namedtuple
+from functools import partial
+
+from aniso8601.builders import (
+    BaseTimeBuilder,
+    DatetimeTuple,
+    DateTuple,
+    Limit,
+    TimeTuple,
+    TupleBuilder,
+    cast,
+    range_check,
+)
+from aniso8601.exceptions import (
+    DayOutOfBoundsError,
+    HoursOutOfBoundsError,
+    ISOFormatError,
+    LeapSecondError,
+    MidnightBoundsError,
+    MinutesOutOfBoundsError,
+    MonthOutOfBoundsError,
+    SecondsOutOfBoundsError,
+    WeekOutOfBoundsError,
+    YearOutOfBoundsError,
+)
+from aniso8601.utcoffset import UTCOffset
+
+DAYS_PER_YEAR = 365
+DAYS_PER_MONTH = 30
+DAYS_PER_WEEK = 7
+
+HOURS_PER_DAY = 24
+
+MINUTES_PER_HOUR = 60
+MINUTES_PER_DAY = MINUTES_PER_HOUR * HOURS_PER_DAY
+
+SECONDS_PER_MINUTE = 60
+SECONDS_PER_DAY = MINUTES_PER_DAY * SECONDS_PER_MINUTE
+
+MICROSECONDS_PER_SECOND = int(1e6)
+
+MICROSECONDS_PER_MINUTE = 60 * MICROSECONDS_PER_SECOND
+MICROSECONDS_PER_HOUR = 60 * MICROSECONDS_PER_MINUTE
+MICROSECONDS_PER_DAY = 24 * MICROSECONDS_PER_HOUR
+MICROSECONDS_PER_WEEK = 7 * MICROSECONDS_PER_DAY
+MICROSECONDS_PER_MONTH = DAYS_PER_MONTH * MICROSECONDS_PER_DAY
+MICROSECONDS_PER_YEAR = DAYS_PER_YEAR * MICROSECONDS_PER_DAY
+
+TIMEDELTA_MAX_DAYS = datetime.timedelta.max.days
+
+FractionalComponent = namedtuple(
+    "FractionalComponent", ["principal", "microsecondremainder"]
+)
+
+
+def year_range_check(valuestr, limit):
+    YYYYstr = valuestr
+
+    # Truncated dates, like '19', refer to 1900-1999 inclusive,
+    # we simply parse to 1900
+    if len(valuestr) < 4:
+        # Shift 0s in from the left to form complete year
+        YYYYstr = valuestr.ljust(4, "0")
+
+    return range_check(YYYYstr, limit)
+
+
+def fractional_range_check(conversion, valuestr, limit):
+    if valuestr is None:
+        return None
+
+    if "." in valuestr:
+        castfunc = partial(_cast_to_fractional_component, conversion)
+    else:
+        castfunc = int
+
+    value = cast(valuestr, castfunc, thrownmessage=limit.casterrorstring)
+
+    if type(value) is FractionalComponent:
+        tocheck = float(valuestr)
+    else:
+        tocheck = int(valuestr)
+
+    if limit.min is not None and tocheck < limit.min:
+        raise limit.rangeexception(limit.rangeerrorstring)
+
+    if limit.max is not None and tocheck > limit.max:
+        raise limit.rangeexception(limit.rangeerrorstring)
+
+    return value
+
+
+def _cast_to_fractional_component(conversion, floatstr):
+    # Splits a string with a decimal point into an int, and
+    # int representing the floating point remainder as a number
+    # of microseconds, determined by multiplying by conversion
+    intpart, floatpart = floatstr.split(".")
+
+    intvalue = int(intpart)
+    preconvertedvalue = int(floatpart)
+
+    convertedvalue = (preconvertedvalue * conversion) // (10 ** len(floatpart))
+
+    return FractionalComponent(intvalue, convertedvalue)
+
+
+class PythonTimeBuilder(BaseTimeBuilder):
+    # 0000 (1 BC) is not representable as a Python date
+    DATE_YYYY_LIMIT = Limit(
+        "Invalid year string.",
+        datetime.MINYEAR,
+        datetime.MAXYEAR,
+        YearOutOfBoundsError,
+        "Year must be between {0}..{1}.".format(datetime.MINYEAR, datetime.MAXYEAR),
+        year_range_check,
+    )
+    TIME_HH_LIMIT = Limit(
+        "Invalid hour string.",
+        0,
+        24,
+        HoursOutOfBoundsError,
+        "Hour must be between 0..24 with " "24 representing midnight.",
+        partial(fractional_range_check, MICROSECONDS_PER_HOUR),
+    )
+    TIME_MM_LIMIT = Limit(
+        "Invalid minute string.",
+        0,
+        59,
+        MinutesOutOfBoundsError,
+        "Minute must be between 0..59.",
+        partial(fractional_range_check, MICROSECONDS_PER_MINUTE),
+    )
+    TIME_SS_LIMIT = Limit(
+        "Invalid second string.",
+        0,
+        60,
+        SecondsOutOfBoundsError,
+        "Second must be between 0..60 with " "60 representing a leap second.",
+        partial(fractional_range_check, MICROSECONDS_PER_SECOND),
+    )
+    DURATION_PNY_LIMIT = Limit(
+        "Invalid year duration string.",
+        None,
+        None,
+        YearOutOfBoundsError,
+        None,
+        partial(fractional_range_check, MICROSECONDS_PER_YEAR),
+    )
+    DURATION_PNM_LIMIT = Limit(
+        "Invalid month duration string.",
+        None,
+        None,
+        MonthOutOfBoundsError,
+        None,
+        partial(fractional_range_check, MICROSECONDS_PER_MONTH),
+    )
+    DURATION_PNW_LIMIT = Limit(
+        "Invalid week duration string.",
+        None,
+        None,
+        WeekOutOfBoundsError,
+        None,
+        partial(fractional_range_check, MICROSECONDS_PER_WEEK),
+    )
+    DURATION_PND_LIMIT = Limit(
+        "Invalid day duration string.",
+        None,
+        None,
+        DayOutOfBoundsError,
+        None,
+        partial(fractional_range_check, MICROSECONDS_PER_DAY),
+    )
+    DURATION_TNH_LIMIT = Limit(
+        "Invalid hour duration string.",
+        None,
+        None,
+        HoursOutOfBoundsError,
+        None,
+        partial(fractional_range_check, MICROSECONDS_PER_HOUR),
+    )
+    DURATION_TNM_LIMIT = Limit(
+        "Invalid minute duration string.",
+        None,
+        None,
+        MinutesOutOfBoundsError,
+        None,
+        partial(fractional_range_check, MICROSECONDS_PER_MINUTE),
+    )
+    DURATION_TNS_LIMIT = Limit(
+        "Invalid second duration string.",
+        None,
+        None,
+        SecondsOutOfBoundsError,
+        None,
+        partial(fractional_range_check, MICROSECONDS_PER_SECOND),
+    )
+
+    DATE_RANGE_DICT = BaseTimeBuilder.DATE_RANGE_DICT
+    DATE_RANGE_DICT["YYYY"] = DATE_YYYY_LIMIT
+
+    TIME_RANGE_DICT = {"hh": TIME_HH_LIMIT, "mm": TIME_MM_LIMIT, "ss": TIME_SS_LIMIT}
+
+    DURATION_RANGE_DICT = {
+        "PnY": DURATION_PNY_LIMIT,
+        "PnM": DURATION_PNM_LIMIT,
+        "PnW": DURATION_PNW_LIMIT,
+        "PnD": DURATION_PND_LIMIT,
+        "TnH": DURATION_TNH_LIMIT,
+        "TnM": DURATION_TNM_LIMIT,
+        "TnS": DURATION_TNS_LIMIT,
+    }
+
+    @classmethod
+    def build_date(cls, YYYY=None, MM=None, DD=None, Www=None, D=None, DDD=None):
+        YYYY, MM, DD, Www, D, DDD = cls.range_check_date(YYYY, MM, DD, Www, D, DDD)
+
+        if MM is None:
+            MM = 1
+
+        if DD is None:
+            DD = 1
+
+        if DDD is not None:
+            return PythonTimeBuilder._build_ordinal_date(YYYY, DDD)
+
+        if Www is not None:
+            return PythonTimeBuilder._build_week_date(YYYY, Www, isoday=D)
+
+        return datetime.date(YYYY, MM, DD)
+
+    @classmethod
+    def build_time(cls, hh=None, mm=None, ss=None, tz=None):
+        # Builds a time from the given parts, handling fractional arguments
+        # where necessary
+        hours = 0
+        minutes = 0
+        seconds = 0
+        microseconds = 0
+
+        hh, mm, ss, tz = cls.range_check_time(hh, mm, ss, tz)
+
+        if type(hh) is FractionalComponent:
+            hours = hh.principal
+            microseconds = hh.microsecondremainder
+        elif hh is not None:
+            hours = hh
+
+        if type(mm) is FractionalComponent:
+            minutes = mm.principal
+            microseconds = mm.microsecondremainder
+        elif mm is not None:
+            minutes = mm
+
+        if type(ss) is FractionalComponent:
+            seconds = ss.principal
+            microseconds = ss.microsecondremainder
+        elif ss is not None:
+            seconds = ss
+
+        (
+            hours,
+            minutes,
+            seconds,
+            microseconds,
+        ) = PythonTimeBuilder._distribute_microseconds(
+            microseconds,
+            (hours, minutes, seconds),
+            (MICROSECONDS_PER_HOUR, MICROSECONDS_PER_MINUTE, MICROSECONDS_PER_SECOND),
+        )
+
+        # Move midnight into range
+        if hours == 24:
+            hours = 0
+
+        # Datetimes don't handle fractional components, so we use a timedelta
+        if tz is not None:
+            return (
+                datetime.datetime(
+                    1, 1, 1, hour=hours, minute=minutes, tzinfo=cls._build_object(tz)
+                )
+                + datetime.timedelta(seconds=seconds, microseconds=microseconds)
+            ).timetz()
+
+        return (
+            datetime.datetime(1, 1, 1, hour=hours, minute=minutes)
+            + datetime.timedelta(seconds=seconds, microseconds=microseconds)
+        ).time()
+
+    @classmethod
+    def build_datetime(cls, date, time):
+        return datetime.datetime.combine(
+            cls._build_object(date), cls._build_object(time)
+        )
+
+    @classmethod
+    def build_duration(
+        cls, PnY=None, PnM=None, PnW=None, PnD=None, TnH=None, TnM=None, TnS=None
+    ):
+        # PnY and PnM will be distributed to PnD, microsecond remainder to TnS
+        PnY, PnM, PnW, PnD, TnH, TnM, TnS = cls.range_check_duration(
+            PnY, PnM, PnW, PnD, TnH, TnM, TnS
+        )
+
+        seconds = TnS.principal
+        microseconds = TnS.microsecondremainder
+
+        return datetime.timedelta(
+            days=PnD,
+            seconds=seconds,
+            microseconds=microseconds,
+            minutes=TnM,
+            hours=TnH,
+            weeks=PnW,
+        )
+
+    @classmethod
+    def build_interval(cls, start=None, end=None, duration=None):
+        start, end, duration = cls.range_check_interval(start, end, duration)
+
+        if start is not None and end is not None:
+            # <start>/<end>
+            startobject = cls._build_object(start)
+            endobject = cls._build_object(end)
+
+            return (startobject, endobject)
+
+        durationobject = cls._build_object(duration)
+
+        # Determine if datetime promotion is required
+        datetimerequired = (
+            duration.TnH is not None
+            or duration.TnM is not None
+            or duration.TnS is not None
+            or durationobject.seconds != 0
+            or durationobject.microseconds != 0
+        )
+
+        if end is not None:
+            # <duration>/<end>
+            endobject = cls._build_object(end)
+
+            # Range check
+            if type(end) is DateTuple and datetimerequired is True:
+                # <end> is a date, and <duration> requires datetime resolution
+                return (
+                    endobject,
+                    cls.build_datetime(end, TupleBuilder.build_time()) - durationobject,
+                )
+
+            return (endobject, endobject - durationobject)
+
+        # <start>/<duration>
+        startobject = cls._build_object(start)
+
+        # Range check
+        if type(start) is DateTuple and datetimerequired is True:
+            # <start> is a date, and <duration> requires datetime resolution
+            return (
+                startobject,
+                cls.build_datetime(start, TupleBuilder.build_time()) + durationobject,
+            )
+
+        return (startobject, startobject + durationobject)
+
+    @classmethod
+    def build_repeating_interval(cls, R=None, Rnn=None, interval=None):
+        startobject = None
+        endobject = None
+
+        R, Rnn, interval = cls.range_check_repeating_interval(R, Rnn, interval)
+
+        if interval.start is not None:
+            startobject = cls._build_object(interval.start)
+
+        if interval.end is not None:
+            endobject = cls._build_object(interval.end)
+
+        if interval.duration is not None:
+            durationobject = cls._build_object(interval.duration)
+        else:
+            durationobject = endobject - startobject
+
+        if R is True:
+            if startobject is not None:
+                return cls._date_generator_unbounded(startobject, durationobject)
+
+            return cls._date_generator_unbounded(endobject, -durationobject)
+
+        iterations = int(Rnn)
+
+        if startobject is not None:
+            return cls._date_generator(startobject, durationobject, iterations)
+
+        return cls._date_generator(endobject, -durationobject, iterations)
+
+    @classmethod
+    def build_timezone(cls, negative=None, Z=None, hh=None, mm=None, name=""):
+        negative, Z, hh, mm, name = cls.range_check_timezone(negative, Z, hh, mm, name)
+
+        if Z is True:
+            # Z -> UTC
+            return UTCOffset(name="UTC", minutes=0)
+
+        tzhour = int(hh)
+
+        if mm is not None:
+            tzminute = int(mm)
+        else:
+            tzminute = 0
+
+        if negative is True:
+            return UTCOffset(name=name, minutes=-(tzhour * 60 + tzminute))
+
+        return UTCOffset(name=name, minutes=tzhour * 60 + tzminute)
+
+    @classmethod
+    def range_check_duration(
+        cls,
+        PnY=None,
+        PnM=None,
+        PnW=None,
+        PnD=None,
+        TnH=None,
+        TnM=None,
+        TnS=None,
+        rangedict=None,
+    ):
+        years = 0
+        months = 0
+        days = 0
+        weeks = 0
+        hours = 0
+        minutes = 0
+        seconds = 0
+        microseconds = 0
+
+        PnY, PnM, PnW, PnD, TnH, TnM, TnS = BaseTimeBuilder.range_check_duration(
+            PnY, PnM, PnW, PnD, TnH, TnM, TnS, rangedict=cls.DURATION_RANGE_DICT
+        )
+
+        if PnY is not None:
+            if type(PnY) is FractionalComponent:
+                years = PnY.principal
+                microseconds = PnY.microsecondremainder
+            else:
+                years = PnY
+
+            if years * DAYS_PER_YEAR > TIMEDELTA_MAX_DAYS:
+                raise YearOutOfBoundsError("Duration exceeds maximum timedelta size.")
+
+        if PnM is not None:
+            if type(PnM) is FractionalComponent:
+                months = PnM.principal
+                microseconds = PnM.microsecondremainder
+            else:
+                months = PnM
+
+            if months * DAYS_PER_MONTH > TIMEDELTA_MAX_DAYS:
+                raise MonthOutOfBoundsError("Duration exceeds maximum timedelta size.")
+
+        if PnW is not None:
+            if type(PnW) is FractionalComponent:
+                weeks = PnW.principal
+                microseconds = PnW.microsecondremainder
+            else:
+                weeks = PnW
+
+            if weeks * DAYS_PER_WEEK > TIMEDELTA_MAX_DAYS:
+                raise WeekOutOfBoundsError("Duration exceeds maximum timedelta size.")
+
+        if PnD is not None:
+            if type(PnD) is FractionalComponent:
+                days = PnD.principal
+                microseconds = PnD.microsecondremainder
+            else:
+                days = PnD
+
+            if days > TIMEDELTA_MAX_DAYS:
+                raise DayOutOfBoundsError("Duration exceeds maximum timedelta size.")
+
+        if TnH is not None:
+            if type(TnH) is FractionalComponent:
+                hours = TnH.principal
+                microseconds = TnH.microsecondremainder
+            else:
+                hours = TnH
+
+            if hours // HOURS_PER_DAY > TIMEDELTA_MAX_DAYS:
+                raise HoursOutOfBoundsError("Duration exceeds maximum timedelta size.")
+
+        if TnM is not None:
+            if type(TnM) is FractionalComponent:
+                minutes = TnM.principal
+                microseconds = TnM.microsecondremainder
+            else:
+                minutes = TnM
+
+            if minutes // MINUTES_PER_DAY > TIMEDELTA_MAX_DAYS:
+                raise MinutesOutOfBoundsError(
+                    "Duration exceeds maximum timedelta size."
+                )
+
+        if TnS is not None:
+            if type(TnS) is FractionalComponent:
+                seconds = TnS.principal
+                microseconds = TnS.microsecondremainder
+            else:
+                seconds = TnS
+
+            if seconds // SECONDS_PER_DAY > TIMEDELTA_MAX_DAYS:
+                raise SecondsOutOfBoundsError(
+                    "Duration exceeds maximum timedelta size."
+                )
+
+        (
+            years,
+            months,
+            weeks,
+            days,
+            hours,
+            minutes,
+            seconds,
+            microseconds,
+        ) = PythonTimeBuilder._distribute_microseconds(
+            microseconds,
+            (years, months, weeks, days, hours, minutes, seconds),
+            (
+                MICROSECONDS_PER_YEAR,
+                MICROSECONDS_PER_MONTH,
+                MICROSECONDS_PER_WEEK,
+                MICROSECONDS_PER_DAY,
+                MICROSECONDS_PER_HOUR,
+                MICROSECONDS_PER_MINUTE,
+                MICROSECONDS_PER_SECOND,
+            ),
+        )
+
+        # Note that weeks can be handled without conversion to days
+        totaldays = years * DAYS_PER_YEAR + months * DAYS_PER_MONTH + days
+
+        # Check against timedelta limits
+        if (
+            totaldays
+            + weeks * DAYS_PER_WEEK
+            + hours // HOURS_PER_DAY
+            + minutes // MINUTES_PER_DAY
+            + seconds // SECONDS_PER_DAY
+            > TIMEDELTA_MAX_DAYS
+        ):
+            raise DayOutOfBoundsError("Duration exceeds maximum timedelta size.")
+
+        return (
+            None,
+            None,
+            weeks,
+            totaldays,
+            hours,
+            minutes,
+            FractionalComponent(seconds, microseconds),
+        )
+
+    @classmethod
+    def range_check_interval(cls, start=None, end=None, duration=None):
+        # Handles concise format, range checks any potential durations
+        if start is not None and end is not None:
+            # <start>/<end>
+            # Handle concise format
+            if cls._is_interval_end_concise(end) is True:
+                end = cls._combine_concise_interval_tuples(start, end)
+
+            return (start, end, duration)
+
+        durationobject = cls._build_object(duration)
+
+        if end is not None:
+            # <duration>/<end>
+            endobject = cls._build_object(end)
+
+            # Range check
+            if type(end) is DateTuple:
+                enddatetime = cls.build_datetime(end, TupleBuilder.build_time())
+
+                if enddatetime - datetime.datetime.min < durationobject:
+                    raise YearOutOfBoundsError("Interval end less than minimium date.")
+            else:
+                mindatetime = datetime.datetime.min
+
+                if end.time.tz is not None:
+                    mindatetime = mindatetime.replace(tzinfo=endobject.tzinfo)
+
+                if endobject - mindatetime < durationobject:
+                    raise YearOutOfBoundsError("Interval end less than minimium date.")
+        else:
+            # <start>/<duration>
+            startobject = cls._build_object(start)
+
+            # Range check
+            if type(start) is DateTuple:
+                startdatetime = cls.build_datetime(start, TupleBuilder.build_time())
+
+                if datetime.datetime.max - startdatetime < durationobject:
+                    raise YearOutOfBoundsError(
+                        "Interval end greater than maximum date."
+                    )
+            else:
+                maxdatetime = datetime.datetime.max
+
+                if start.time.tz is not None:
+                    maxdatetime = maxdatetime.replace(tzinfo=startobject.tzinfo)
+
+                if maxdatetime - startobject < durationobject:
+                    raise YearOutOfBoundsError(
+                        "Interval end greater than maximum date."
+                    )
+
+        return (start, end, duration)
+
+    @staticmethod
+    def _build_week_date(isoyear, isoweek, isoday=None):
+        if isoday is None:
+            return PythonTimeBuilder._iso_year_start(isoyear) + datetime.timedelta(
+                weeks=isoweek - 1
+            )
+
+        return PythonTimeBuilder._iso_year_start(isoyear) + datetime.timedelta(
+            weeks=isoweek - 1, days=isoday - 1
+        )
+
+    @staticmethod
+    def _build_ordinal_date(isoyear, isoday):
+        # Day of year to a date
+        # https://stackoverflow.com/questions/2427555/python-question-year-and-day-of-year-to-date
+        builtdate = datetime.date(isoyear, 1, 1) + datetime.timedelta(days=isoday - 1)
+
+        return builtdate
+
+    @staticmethod
+    def _iso_year_start(isoyear):
+        # Given an ISO year, returns the equivalent of the start of the year
+        # on the Gregorian calendar (which is used by Python)
+        # Stolen from:
+        # http://stackoverflow.com/questions/304256/whats-the-best-way-to-find-the-inverse-of-datetime-isocalendar
+
+        # Determine the location of the 4th of January, the first week of
+        # the ISO year is the week containing the 4th of January
+        # http://en.wikipedia.org/wiki/ISO_week_date
+        fourth_jan = datetime.date(isoyear, 1, 4)
+
+        # Note the conversion from ISO day (1 - 7) and Python day (0 - 6)
+        delta = datetime.timedelta(days=fourth_jan.isoweekday() - 1)
+
+        # Return the start of the year
+        return fourth_jan - delta
+
+    @staticmethod
+    def _date_generator(startdate, timedelta, iterations):
+        currentdate = startdate
+        currentiteration = 0
+
+        while currentiteration < iterations:
+            yield currentdate
+
+            # Update the values
+            currentdate += timedelta
+            currentiteration += 1
+
+    @staticmethod
+    def _date_generator_unbounded(startdate, timedelta):
+        currentdate = startdate
+
+        while True:
+            yield currentdate
+
+            # Update the value
+            currentdate += timedelta
+
+    @staticmethod
+    def _distribute_microseconds(todistribute, recipients, reductions):
+        # Given a number of microseconds as int, a tuple of ints length n
+        # to distribute to, and a tuple of ints length n to divide todistribute
+        # by (from largest to smallest), returns a tuple of length n + 1, with
+        # todistribute divided across recipients using the reductions, with
+        # the final remainder returned as the final tuple member
+        results = []
+
+        remainder = todistribute
+
+        for index, reduction in enumerate(reductions):
+            additional, remainder = divmod(remainder, reduction)
+
+            results.append(recipients[index] + additional)
+
+        # Always return the remaining microseconds
+        results.append(remainder)
+
+        return tuple(results)
diff --git a/libs/aniso8601/builders/tests/__init__.py b/libs/aniso8601/builders/tests/__init__.py
new file mode 100644
index 000000000..1a94e017a
--- /dev/null
+++ b/libs/aniso8601/builders/tests/__init__.py
@@ -0,0 +1,7 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
diff --git a/libs/aniso8601/builders/tests/test_init.py b/libs/aniso8601/builders/tests/test_init.py
new file mode 100644
index 000000000..7c9f092c7
--- /dev/null
+++ b/libs/aniso8601/builders/tests/test_init.py
@@ -0,0 +1,838 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+import aniso8601
+from aniso8601.builders import (
+    BaseTimeBuilder,
+    DatetimeTuple,
+    DateTuple,
+    DurationTuple,
+    IntervalTuple,
+    RepeatingIntervalTuple,
+    TimeTuple,
+    TimezoneTuple,
+    TupleBuilder,
+    cast,
+)
+from aniso8601.exceptions import (
+    DayOutOfBoundsError,
+    HoursOutOfBoundsError,
+    ISOFormatError,
+    LeapSecondError,
+    MidnightBoundsError,
+    MinutesOutOfBoundsError,
+    MonthOutOfBoundsError,
+    SecondsOutOfBoundsError,
+    WeekOutOfBoundsError,
+)
+from aniso8601.tests.compat import mock
+
+
+class LeapSecondSupportingTestBuilder(BaseTimeBuilder):
+    LEAP_SECONDS_SUPPORTED = True
+
+
+class TestBuilderFunctions(unittest.TestCase):
+    def test_cast(self):
+        self.assertEqual(cast("1", int), 1)
+        self.assertEqual(cast("-2", int), -2)
+        self.assertEqual(cast("3", float), float(3))
+        self.assertEqual(cast("-4", float), float(-4))
+        self.assertEqual(cast("5.6", float), 5.6)
+        self.assertEqual(cast("-7.8", float), -7.8)
+
+    def test_cast_exception(self):
+        with self.assertRaises(ISOFormatError):
+            cast("asdf", int)
+
+        with self.assertRaises(ISOFormatError):
+            cast("asdf", float)
+
+    def test_cast_caughtexception(self):
+        def tester(value):
+            raise RuntimeError
+
+        with self.assertRaises(ISOFormatError):
+            cast("asdf", tester, caughtexceptions=(RuntimeError,))
+
+    def test_cast_thrownexception(self):
+        with self.assertRaises(RuntimeError):
+            cast("asdf", int, thrownexception=RuntimeError)
+
+
+class TestBaseTimeBuilder(unittest.TestCase):
+    def test_build_date(self):
+        with self.assertRaises(NotImplementedError):
+            BaseTimeBuilder.build_date()
+
+    def test_build_time(self):
+        with self.assertRaises(NotImplementedError):
+            BaseTimeBuilder.build_time()
+
+    def test_build_datetime(self):
+        with self.assertRaises(NotImplementedError):
+            BaseTimeBuilder.build_datetime(None, None)
+
+    def test_build_duration(self):
+        with self.assertRaises(NotImplementedError):
+            BaseTimeBuilder.build_duration()
+
+    def test_build_interval(self):
+        with self.assertRaises(NotImplementedError):
+            BaseTimeBuilder.build_interval()
+
+    def test_build_repeating_interval(self):
+        with self.assertRaises(NotImplementedError):
+            BaseTimeBuilder.build_repeating_interval()
+
+    def test_build_timezone(self):
+        with self.assertRaises(NotImplementedError):
+            BaseTimeBuilder.build_timezone()
+
+    def test_range_check_date(self):
+        # Check the calendar for day ranges
+        with self.assertRaises(DayOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="0007", MM="02", DD="30")
+
+        with self.assertRaises(DayOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="0007", DDD="366")
+
+        with self.assertRaises(MonthOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="4333", MM="30", DD="30")
+
+        # 0 isn't a valid week number
+        with self.assertRaises(WeekOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="2003", Www="00")
+
+        # Week must not be larger than 53
+        with self.assertRaises(WeekOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="2004", Www="54")
+
+        # 0 isn't a valid day number
+        with self.assertRaises(DayOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="2001", Www="02", D="0")
+
+        # Day must not be larger than 7
+        with self.assertRaises(DayOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="2001", Www="02", D="8")
+
+        with self.assertRaises(DayOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="1981", DDD="000")
+
+        # Day must be 365, or 366, not larger
+        with self.assertRaises(DayOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="1234", DDD="000")
+
+        with self.assertRaises(DayOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="1234", DDD="367")
+
+        # https://bitbucket.org/nielsenb/aniso8601/issues/14/parsing-ordinal-dates-should-only-allow
+        with self.assertRaises(DayOutOfBoundsError):
+            BaseTimeBuilder.range_check_date(YYYY="1981", DDD="366")
+
+        # Make sure Nones pass through unmodified
+        self.assertEqual(
+            BaseTimeBuilder.range_check_date(rangedict={}),
+            (None, None, None, None, None, None),
+        )
+
+    def test_range_check_time(self):
+        # Leap seconds not supported
+        # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+        # https://bitbucket.org/nielsenb/aniso8601/issues/13/parsing-of-leap-second-gives-wildly
+        with self.assertRaises(LeapSecondError):
+            BaseTimeBuilder.range_check_time(hh="23", mm="59", ss="60")
+
+        with self.assertRaises(SecondsOutOfBoundsError):
+            BaseTimeBuilder.range_check_time(hh="00", mm="00", ss="60")
+
+        with self.assertRaises(SecondsOutOfBoundsError):
+            BaseTimeBuilder.range_check_time(hh="00", mm="00", ss="61")
+
+        with self.assertRaises(MinutesOutOfBoundsError):
+            BaseTimeBuilder.range_check_time(hh="00", mm="61")
+
+        with self.assertRaises(MinutesOutOfBoundsError):
+            BaseTimeBuilder.range_check_time(hh="00", mm="60")
+
+        with self.assertRaises(MinutesOutOfBoundsError):
+            BaseTimeBuilder.range_check_time(hh="00", mm="60.1")
+
+        with self.assertRaises(HoursOutOfBoundsError):
+            BaseTimeBuilder.range_check_time(hh="25")
+
+        # Hour 24 can only represent midnight
+        with self.assertRaises(MidnightBoundsError):
+            BaseTimeBuilder.range_check_time(hh="24", mm="00", ss="01")
+
+        with self.assertRaises(MidnightBoundsError):
+            BaseTimeBuilder.range_check_time(hh="24", mm="00.1")
+
+        with self.assertRaises(MidnightBoundsError):
+            BaseTimeBuilder.range_check_time(hh="24", mm="01")
+
+        with self.assertRaises(MidnightBoundsError):
+            BaseTimeBuilder.range_check_time(hh="24.1")
+
+        # Leap seconds not supported
+        # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+        # https://bitbucket.org/nielsenb/aniso8601/issues/13/parsing-of-leap-second-gives-wildly
+        with self.assertRaises(LeapSecondError):
+            BaseTimeBuilder.range_check_time(hh="23", mm="59", ss="60")
+
+        # Make sure Nones pass through unmodified
+        self.assertEqual(
+            BaseTimeBuilder.range_check_time(rangedict={}), (None, None, None, None)
+        )
+
+    def test_range_check_time_leap_seconds_supported(self):
+        self.assertEqual(
+            LeapSecondSupportingTestBuilder.range_check_time(hh="23", mm="59", ss="60"),
+            (23, 59, 60, None),
+        )
+
+        with self.assertRaises(SecondsOutOfBoundsError):
+            LeapSecondSupportingTestBuilder.range_check_time(hh="01", mm="02", ss="60")
+
+    def test_range_check_duration(self):
+        self.assertEqual(
+            BaseTimeBuilder.range_check_duration(),
+            (None, None, None, None, None, None, None),
+        )
+
+        self.assertEqual(
+            BaseTimeBuilder.range_check_duration(rangedict={}),
+            (None, None, None, None, None, None, None),
+        )
+
+    def test_range_check_repeating_interval(self):
+        self.assertEqual(
+            BaseTimeBuilder.range_check_repeating_interval(), (None, None, None)
+        )
+
+        self.assertEqual(
+            BaseTimeBuilder.range_check_repeating_interval(rangedict={}),
+            (None, None, None),
+        )
+
+    def test_range_check_timezone(self):
+        self.assertEqual(
+            BaseTimeBuilder.range_check_timezone(), (None, None, None, None, "")
+        )
+
+        self.assertEqual(
+            BaseTimeBuilder.range_check_timezone(rangedict={}),
+            (None, None, None, None, ""),
+        )
+
+    def test_build_object(self):
+        datetest = (
+            DateTuple("1", "2", "3", "4", "5", "6"),
+            {"YYYY": "1", "MM": "2", "DD": "3", "Www": "4", "D": "5", "DDD": "6"},
+        )
+
+        timetest = (
+            TimeTuple("1", "2", "3", TimezoneTuple(False, False, "4", "5", "tz name")),
+            {
+                "hh": "1",
+                "mm": "2",
+                "ss": "3",
+                "tz": TimezoneTuple(False, False, "4", "5", "tz name"),
+            },
+        )
+
+        datetimetest = (
+            DatetimeTuple(
+                DateTuple("1", "2", "3", "4", "5", "6"),
+                TimeTuple(
+                    "7", "8", "9", TimezoneTuple(True, False, "10", "11", "tz name")
+                ),
+            ),
+            (
+                DateTuple("1", "2", "3", "4", "5", "6"),
+                TimeTuple(
+                    "7", "8", "9", TimezoneTuple(True, False, "10", "11", "tz name")
+                ),
+            ),
+        )
+
+        durationtest = (
+            DurationTuple("1", "2", "3", "4", "5", "6", "7"),
+            {
+                "PnY": "1",
+                "PnM": "2",
+                "PnW": "3",
+                "PnD": "4",
+                "TnH": "5",
+                "TnM": "6",
+                "TnS": "7",
+            },
+        )
+
+        intervaltests = (
+            (
+                IntervalTuple(
+                    DateTuple("1", "2", "3", "4", "5", "6"),
+                    DateTuple("7", "8", "9", "10", "11", "12"),
+                    None,
+                ),
+                {
+                    "start": DateTuple("1", "2", "3", "4", "5", "6"),
+                    "end": DateTuple("7", "8", "9", "10", "11", "12"),
+                    "duration": None,
+                },
+            ),
+            (
+                IntervalTuple(
+                    DateTuple("1", "2", "3", "4", "5", "6"),
+                    None,
+                    DurationTuple("7", "8", "9", "10", "11", "12", "13"),
+                ),
+                {
+                    "start": DateTuple("1", "2", "3", "4", "5", "6"),
+                    "end": None,
+                    "duration": DurationTuple("7", "8", "9", "10", "11", "12", "13"),
+                },
+            ),
+            (
+                IntervalTuple(
+                    None,
+                    TimeTuple(
+                        "1", "2", "3", TimezoneTuple(True, False, "4", "5", "tz name")
+                    ),
+                    DurationTuple("6", "7", "8", "9", "10", "11", "12"),
+                ),
+                {
+                    "start": None,
+                    "end": TimeTuple(
+                        "1", "2", "3", TimezoneTuple(True, False, "4", "5", "tz name")
+                    ),
+                    "duration": DurationTuple("6", "7", "8", "9", "10", "11", "12"),
+                },
+            ),
+        )
+
+        repeatingintervaltests = (
+            (
+                RepeatingIntervalTuple(
+                    True,
+                    None,
+                    IntervalTuple(
+                        DateTuple("1", "2", "3", "4", "5", "6"),
+                        DateTuple("7", "8", "9", "10", "11", "12"),
+                        None,
+                    ),
+                ),
+                {
+                    "R": True,
+                    "Rnn": None,
+                    "interval": IntervalTuple(
+                        DateTuple("1", "2", "3", "4", "5", "6"),
+                        DateTuple("7", "8", "9", "10", "11", "12"),
+                        None,
+                    ),
+                },
+            ),
+            (
+                RepeatingIntervalTuple(
+                    False,
+                    "1",
+                    IntervalTuple(
+                        DatetimeTuple(
+                            DateTuple("2", "3", "4", "5", "6", "7"),
+                            TimeTuple("8", "9", "10", None),
+                        ),
+                        DatetimeTuple(
+                            DateTuple("11", "12", "13", "14", "15", "16"),
+                            TimeTuple("17", "18", "19", None),
+                        ),
+                        None,
+                    ),
+                ),
+                {
+                    "R": False,
+                    "Rnn": "1",
+                    "interval": IntervalTuple(
+                        DatetimeTuple(
+                            DateTuple("2", "3", "4", "5", "6", "7"),
+                            TimeTuple("8", "9", "10", None),
+                        ),
+                        DatetimeTuple(
+                            DateTuple("11", "12", "13", "14", "15", "16"),
+                            TimeTuple("17", "18", "19", None),
+                        ),
+                        None,
+                    ),
+                },
+            ),
+        )
+
+        timezonetest = (
+            TimezoneTuple(False, False, "1", "2", "+01:02"),
+            {"negative": False, "Z": False, "hh": "1", "mm": "2", "name": "+01:02"},
+        )
+
+        with mock.patch.object(
+            aniso8601.builders.BaseTimeBuilder, "build_date"
+        ) as mock_build:
+            mock_build.return_value = datetest[0]
+
+            result = BaseTimeBuilder._build_object(datetest[0])
+
+            self.assertEqual(result, datetest[0])
+            mock_build.assert_called_once_with(**datetest[1])
+
+        with mock.patch.object(
+            aniso8601.builders.BaseTimeBuilder, "build_time"
+        ) as mock_build:
+            mock_build.return_value = timetest[0]
+
+            result = BaseTimeBuilder._build_object(timetest[0])
+
+            self.assertEqual(result, timetest[0])
+            mock_build.assert_called_once_with(**timetest[1])
+
+        with mock.patch.object(
+            aniso8601.builders.BaseTimeBuilder, "build_datetime"
+        ) as mock_build:
+            mock_build.return_value = datetimetest[0]
+
+            result = BaseTimeBuilder._build_object(datetimetest[0])
+
+            self.assertEqual(result, datetimetest[0])
+            mock_build.assert_called_once_with(*datetimetest[1])
+
+        with mock.patch.object(
+            aniso8601.builders.BaseTimeBuilder, "build_duration"
+        ) as mock_build:
+            mock_build.return_value = durationtest[0]
+
+            result = BaseTimeBuilder._build_object(durationtest[0])
+
+            self.assertEqual(result, durationtest[0])
+            mock_build.assert_called_once_with(**durationtest[1])
+
+        for intervaltest in intervaltests:
+            with mock.patch.object(
+                aniso8601.builders.BaseTimeBuilder, "build_interval"
+            ) as mock_build:
+                mock_build.return_value = intervaltest[0]
+
+                result = BaseTimeBuilder._build_object(intervaltest[0])
+
+                self.assertEqual(result, intervaltest[0])
+                mock_build.assert_called_once_with(**intervaltest[1])
+
+        for repeatingintervaltest in repeatingintervaltests:
+            with mock.patch.object(
+                aniso8601.builders.BaseTimeBuilder, "build_repeating_interval"
+            ) as mock_build:
+                mock_build.return_value = repeatingintervaltest[0]
+
+                result = BaseTimeBuilder._build_object(repeatingintervaltest[0])
+
+                self.assertEqual(result, repeatingintervaltest[0])
+                mock_build.assert_called_once_with(**repeatingintervaltest[1])
+
+        with mock.patch.object(
+            aniso8601.builders.BaseTimeBuilder, "build_timezone"
+        ) as mock_build:
+            mock_build.return_value = timezonetest[0]
+
+            result = BaseTimeBuilder._build_object(timezonetest[0])
+
+            self.assertEqual(result, timezonetest[0])
+            mock_build.assert_called_once_with(**timezonetest[1])
+
+    def test_is_interval_end_concise(self):
+        self.assertTrue(
+            BaseTimeBuilder._is_interval_end_concise(TimeTuple("1", "2", "3", None))
+        )
+        self.assertTrue(
+            BaseTimeBuilder._is_interval_end_concise(
+                DateTuple(None, "2", "3", "4", "5", "6")
+            )
+        )
+        self.assertTrue(
+            BaseTimeBuilder._is_interval_end_concise(
+                DatetimeTuple(
+                    DateTuple(None, "2", "3", "4", "5", "6"),
+                    TimeTuple("7", "8", "9", None),
+                )
+            )
+        )
+
+        self.assertFalse(
+            BaseTimeBuilder._is_interval_end_concise(
+                DateTuple("1", "2", "3", "4", "5", "6")
+            )
+        )
+        self.assertFalse(
+            BaseTimeBuilder._is_interval_end_concise(
+                DatetimeTuple(
+                    DateTuple("1", "2", "3", "4", "5", "6"),
+                    TimeTuple("7", "8", "9", None),
+                )
+            )
+        )
+
+    def test_combine_concise_interval_tuples(self):
+        testtuples = (
+            (
+                DateTuple("2020", "01", "01", None, None, None),
+                DateTuple(None, None, "02", None, None, None),
+                DateTuple("2020", "01", "02", None, None, None),
+            ),
+            (
+                DateTuple("2008", "02", "15", None, None, None),
+                DateTuple(None, "03", "14", None, None, None),
+                DateTuple("2008", "03", "14", None, None, None),
+            ),
+            (
+                DatetimeTuple(
+                    DateTuple("2007", "12", "14", None, None, None),
+                    TimeTuple("13", "30", None, None),
+                ),
+                TimeTuple("15", "30", None, None),
+                DatetimeTuple(
+                    DateTuple("2007", "12", "14", None, None, None),
+                    TimeTuple("15", "30", None, None),
+                ),
+            ),
+            (
+                DatetimeTuple(
+                    DateTuple("2007", "11", "13", None, None, None),
+                    TimeTuple("09", "00", None, None),
+                ),
+                DatetimeTuple(
+                    DateTuple(None, None, "15", None, None, None),
+                    TimeTuple("17", "00", None, None),
+                ),
+                DatetimeTuple(
+                    DateTuple("2007", "11", "15", None, None, None),
+                    TimeTuple("17", "00", None, None),
+                ),
+            ),
+            (
+                DatetimeTuple(
+                    DateTuple("2007", "11", "13", None, None, None),
+                    TimeTuple("00", "00", None, None),
+                ),
+                DatetimeTuple(
+                    DateTuple(None, None, "16", None, None, None),
+                    TimeTuple("00", "00", None, None),
+                ),
+                DatetimeTuple(
+                    DateTuple("2007", "11", "16", None, None, None),
+                    TimeTuple("00", "00", None, None),
+                ),
+            ),
+            (
+                DatetimeTuple(
+                    DateTuple("2007", "11", "13", None, None, None),
+                    TimeTuple(
+                        "09", "00", None, TimezoneTuple(False, True, None, None, "Z")
+                    ),
+                ),
+                DatetimeTuple(
+                    DateTuple(None, None, "15", None, None, None),
+                    TimeTuple("17", "00", None, None),
+                ),
+                DatetimeTuple(
+                    DateTuple("2007", "11", "15", None, None, None),
+                    TimeTuple(
+                        "17", "00", None, TimezoneTuple(False, True, None, None, "Z")
+                    ),
+                ),
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = BaseTimeBuilder._combine_concise_interval_tuples(
+                testtuple[0], testtuple[1]
+            )
+            self.assertEqual(result, testtuple[2])
+
+
+class TestTupleBuilder(unittest.TestCase):
+    def test_build_date(self):
+        datetuple = TupleBuilder.build_date()
+
+        self.assertEqual(datetuple, DateTuple(None, None, None, None, None, None))
+
+        datetuple = TupleBuilder.build_date(
+            YYYY="1", MM="2", DD="3", Www="4", D="5", DDD="6"
+        )
+
+        self.assertEqual(datetuple, DateTuple("1", "2", "3", "4", "5", "6"))
+
+    def test_build_time(self):
+        testtuples = (
+            ({}, TimeTuple(None, None, None, None)),
+            (
+                {"hh": "1", "mm": "2", "ss": "3", "tz": None},
+                TimeTuple("1", "2", "3", None),
+            ),
+            (
+                {
+                    "hh": "1",
+                    "mm": "2",
+                    "ss": "3",
+                    "tz": TimezoneTuple(False, False, "4", "5", "tz name"),
+                },
+                TimeTuple(
+                    "1", "2", "3", TimezoneTuple(False, False, "4", "5", "tz name")
+                ),
+            ),
+        )
+
+        for testtuple in testtuples:
+            self.assertEqual(TupleBuilder.build_time(**testtuple[0]), testtuple[1])
+
+    def test_build_datetime(self):
+        testtuples = (
+            (
+                {
+                    "date": DateTuple("1", "2", "3", "4", "5", "6"),
+                    "time": TimeTuple("7", "8", "9", None),
+                },
+                DatetimeTuple(
+                    DateTuple("1", "2", "3", "4", "5", "6"),
+                    TimeTuple("7", "8", "9", None),
+                ),
+            ),
+            (
+                {
+                    "date": DateTuple("1", "2", "3", "4", "5", "6"),
+                    "time": TimeTuple(
+                        "7", "8", "9", TimezoneTuple(True, False, "10", "11", "tz name")
+                    ),
+                },
+                DatetimeTuple(
+                    DateTuple("1", "2", "3", "4", "5", "6"),
+                    TimeTuple(
+                        "7", "8", "9", TimezoneTuple(True, False, "10", "11", "tz name")
+                    ),
+                ),
+            ),
+        )
+
+        for testtuple in testtuples:
+            self.assertEqual(TupleBuilder.build_datetime(**testtuple[0]), testtuple[1])
+
+    def test_build_duration(self):
+        testtuples = (
+            ({}, DurationTuple(None, None, None, None, None, None, None)),
+            (
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": "3",
+                    "PnD": "4",
+                    "TnH": "5",
+                    "TnM": "6",
+                    "TnS": "7",
+                },
+                DurationTuple("1", "2", "3", "4", "5", "6", "7"),
+            ),
+        )
+
+        for testtuple in testtuples:
+            self.assertEqual(TupleBuilder.build_duration(**testtuple[0]), testtuple[1])
+
+    def test_build_interval(self):
+        testtuples = (
+            ({}, IntervalTuple(None, None, None)),
+            (
+                {
+                    "start": DateTuple("1", "2", "3", "4", "5", "6"),
+                    "end": DateTuple("7", "8", "9", "10", "11", "12"),
+                },
+                IntervalTuple(
+                    DateTuple("1", "2", "3", "4", "5", "6"),
+                    DateTuple("7", "8", "9", "10", "11", "12"),
+                    None,
+                ),
+            ),
+            (
+                {
+                    "start": TimeTuple(
+                        "1", "2", "3", TimezoneTuple(True, False, "7", "8", "tz name")
+                    ),
+                    "end": TimeTuple(
+                        "4", "5", "6", TimezoneTuple(False, False, "9", "10", "tz name")
+                    ),
+                },
+                IntervalTuple(
+                    TimeTuple(
+                        "1", "2", "3", TimezoneTuple(True, False, "7", "8", "tz name")
+                    ),
+                    TimeTuple(
+                        "4", "5", "6", TimezoneTuple(False, False, "9", "10", "tz name")
+                    ),
+                    None,
+                ),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1", "2", "3", "4", "5", "6"),
+                        TimeTuple(
+                            "7",
+                            "8",
+                            "9",
+                            TimezoneTuple(True, False, "10", "11", "tz name"),
+                        ),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("12", "13", "14", "15", "16", "17"),
+                        TimeTuple(
+                            "18",
+                            "19",
+                            "20",
+                            TimezoneTuple(False, False, "21", "22", "tz name"),
+                        ),
+                    ),
+                },
+                IntervalTuple(
+                    DatetimeTuple(
+                        DateTuple("1", "2", "3", "4", "5", "6"),
+                        TimeTuple(
+                            "7",
+                            "8",
+                            "9",
+                            TimezoneTuple(True, False, "10", "11", "tz name"),
+                        ),
+                    ),
+                    DatetimeTuple(
+                        DateTuple("12", "13", "14", "15", "16", "17"),
+                        TimeTuple(
+                            "18",
+                            "19",
+                            "20",
+                            TimezoneTuple(False, False, "21", "22", "tz name"),
+                        ),
+                    ),
+                    None,
+                ),
+            ),
+            (
+                {
+                    "start": DateTuple("1", "2", "3", "4", "5", "6"),
+                    "end": None,
+                    "duration": DurationTuple("7", "8", "9", "10", "11", "12", "13"),
+                },
+                IntervalTuple(
+                    DateTuple("1", "2", "3", "4", "5", "6"),
+                    None,
+                    DurationTuple("7", "8", "9", "10", "11", "12", "13"),
+                ),
+            ),
+            (
+                {
+                    "start": None,
+                    "end": TimeTuple(
+                        "1", "2", "3", TimezoneTuple(True, False, "4", "5", "tz name")
+                    ),
+                    "duration": DurationTuple("6", "7", "8", "9", "10", "11", "12"),
+                },
+                IntervalTuple(
+                    None,
+                    TimeTuple(
+                        "1", "2", "3", TimezoneTuple(True, False, "4", "5", "tz name")
+                    ),
+                    DurationTuple("6", "7", "8", "9", "10", "11", "12"),
+                ),
+            ),
+        )
+
+        for testtuple in testtuples:
+            self.assertEqual(TupleBuilder.build_interval(**testtuple[0]), testtuple[1])
+
+    def test_build_repeating_interval(self):
+        testtuples = (
+            ({}, RepeatingIntervalTuple(None, None, None)),
+            (
+                {
+                    "R": True,
+                    "interval": IntervalTuple(
+                        DateTuple("1", "2", "3", "4", "5", "6"),
+                        DateTuple("7", "8", "9", "10", "11", "12"),
+                        None,
+                    ),
+                },
+                RepeatingIntervalTuple(
+                    True,
+                    None,
+                    IntervalTuple(
+                        DateTuple("1", "2", "3", "4", "5", "6"),
+                        DateTuple("7", "8", "9", "10", "11", "12"),
+                        None,
+                    ),
+                ),
+            ),
+            (
+                {
+                    "R": False,
+                    "Rnn": "1",
+                    "interval": IntervalTuple(
+                        DatetimeTuple(
+                            DateTuple("2", "3", "4", "5", "6", "7"),
+                            TimeTuple("8", "9", "10", None),
+                        ),
+                        DatetimeTuple(
+                            DateTuple("11", "12", "13", "14", "15", "16"),
+                            TimeTuple("17", "18", "19", None),
+                        ),
+                        None,
+                    ),
+                },
+                RepeatingIntervalTuple(
+                    False,
+                    "1",
+                    IntervalTuple(
+                        DatetimeTuple(
+                            DateTuple("2", "3", "4", "5", "6", "7"),
+                            TimeTuple("8", "9", "10", None),
+                        ),
+                        DatetimeTuple(
+                            DateTuple("11", "12", "13", "14", "15", "16"),
+                            TimeTuple("17", "18", "19", None),
+                        ),
+                        None,
+                    ),
+                ),
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = TupleBuilder.build_repeating_interval(**testtuple[0])
+            self.assertEqual(result, testtuple[1])
+
+    def test_build_timezone(self):
+        testtuples = (
+            ({}, TimezoneTuple(None, None, None, None, "")),
+            (
+                {"negative": False, "Z": True, "name": "UTC"},
+                TimezoneTuple(False, True, None, None, "UTC"),
+            ),
+            (
+                {"negative": False, "Z": False, "hh": "1", "mm": "2", "name": "+01:02"},
+                TimezoneTuple(False, False, "1", "2", "+01:02"),
+            ),
+            (
+                {"negative": True, "Z": False, "hh": "1", "mm": "2", "name": "-01:02"},
+                TimezoneTuple(True, False, "1", "2", "-01:02"),
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = TupleBuilder.build_timezone(**testtuple[0])
+            self.assertEqual(result, testtuple[1])
diff --git a/libs/aniso8601/builders/tests/test_python.py b/libs/aniso8601/builders/tests/test_python.py
new file mode 100644
index 000000000..11111a163
--- /dev/null
+++ b/libs/aniso8601/builders/tests/test_python.py
@@ -0,0 +1,1710 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import datetime
+import unittest
+
+from aniso8601 import compat
+from aniso8601.builders import (
+    DatetimeTuple,
+    DateTuple,
+    DurationTuple,
+    IntervalTuple,
+    Limit,
+    TimeTuple,
+    TimezoneTuple,
+)
+from aniso8601.builders.python import (
+    FractionalComponent,
+    PythonTimeBuilder,
+    _cast_to_fractional_component,
+    fractional_range_check,
+    year_range_check,
+)
+from aniso8601.exceptions import (
+    DayOutOfBoundsError,
+    HoursOutOfBoundsError,
+    ISOFormatError,
+    LeapSecondError,
+    MidnightBoundsError,
+    MinutesOutOfBoundsError,
+    MonthOutOfBoundsError,
+    SecondsOutOfBoundsError,
+    WeekOutOfBoundsError,
+    YearOutOfBoundsError,
+)
+from aniso8601.utcoffset import UTCOffset
+
+
+class TestPythonTimeBuilder_UtiltyFunctions(unittest.TestCase):
+    def test_year_range_check(self):
+        yearlimit = Limit(
+            "Invalid year string.",
+            0000,
+            9999,
+            YearOutOfBoundsError,
+            "Year must be between 1..9999.",
+            None,
+        )
+
+        self.assertEqual(year_range_check("1", yearlimit), 1000)
+
+    def test_fractional_range_check(self):
+        limit = Limit(
+            "Invalid string.", -1, 1, ValueError, "Value must be between -1..1.", None
+        )
+
+        self.assertEqual(fractional_range_check(10, "1", limit), 1)
+        self.assertEqual(fractional_range_check(10, "-1", limit), -1)
+        self.assertEqual(
+            fractional_range_check(10, "0.1", limit), FractionalComponent(0, 1)
+        )
+        self.assertEqual(
+            fractional_range_check(10, "-0.1", limit), FractionalComponent(-0, 1)
+        )
+
+        with self.assertRaises(ValueError):
+            fractional_range_check(10, "1.1", limit)
+
+        with self.assertRaises(ValueError):
+            fractional_range_check(10, "-1.1", limit)
+
+    def test_cast_to_fractional_component(self):
+        self.assertEqual(
+            _cast_to_fractional_component(10, "1.1"), FractionalComponent(1, 1)
+        )
+        self.assertEqual(
+            _cast_to_fractional_component(10, "-1.1"), FractionalComponent(-1, 1)
+        )
+
+        self.assertEqual(
+            _cast_to_fractional_component(100, "1.1"), FractionalComponent(1, 10)
+        )
+        self.assertEqual(
+            _cast_to_fractional_component(100, "-1.1"), FractionalComponent(-1, 10)
+        )
+
+
+class TestPythonTimeBuilder(unittest.TestCase):
+    def test_build_date(self):
+        testtuples = (
+            (
+                {
+                    "YYYY": "2013",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(2013, 1, 1),
+            ),
+            (
+                {
+                    "YYYY": "0001",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(1, 1, 1),
+            ),
+            (
+                {
+                    "YYYY": "1900",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(1900, 1, 1),
+            ),
+            (
+                {
+                    "YYYY": "1981",
+                    "MM": "04",
+                    "DD": "05",
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(1981, 4, 5),
+            ),
+            (
+                {
+                    "YYYY": "1981",
+                    "MM": "04",
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(1981, 4, 1),
+            ),
+            (
+                {
+                    "YYYY": "1981",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": "095",
+                },
+                datetime.date(1981, 4, 5),
+            ),
+            (
+                {
+                    "YYYY": "1981",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": "365",
+                },
+                datetime.date(1981, 12, 31),
+            ),
+            (
+                {
+                    "YYYY": "1980",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": "366",
+                },
+                datetime.date(1980, 12, 31),
+            ),
+            # Make sure we shift in zeros
+            (
+                {
+                    "YYYY": "1",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(1000, 1, 1),
+            ),
+            (
+                {
+                    "YYYY": "12",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(1200, 1, 1),
+            ),
+            (
+                {
+                    "YYYY": "123",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(1230, 1, 1),
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = PythonTimeBuilder.build_date(**testtuple[0])
+            self.assertEqual(result, testtuple[1])
+
+        # Test weekday
+        testtuples = (
+            (
+                {
+                    "YYYY": "2004",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "53",
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(2004, 12, 27),
+                0,
+            ),
+            (
+                {
+                    "YYYY": "2009",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "01",
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(2008, 12, 29),
+                0,
+            ),
+            (
+                {
+                    "YYYY": "2010",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "01",
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(2010, 1, 4),
+                0,
+            ),
+            (
+                {
+                    "YYYY": "2009",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "53",
+                    "D": None,
+                    "DDD": None,
+                },
+                datetime.date(2009, 12, 28),
+                0,
+            ),
+            (
+                {
+                    "YYYY": "2009",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "01",
+                    "D": "1",
+                    "DDD": None,
+                },
+                datetime.date(2008, 12, 29),
+                0,
+            ),
+            (
+                {
+                    "YYYY": "2009",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "53",
+                    "D": "7",
+                    "DDD": None,
+                },
+                datetime.date(2010, 1, 3),
+                6,
+            ),
+            (
+                {
+                    "YYYY": "2010",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "01",
+                    "D": "1",
+                    "DDD": None,
+                },
+                datetime.date(2010, 1, 4),
+                0,
+            ),
+            (
+                {
+                    "YYYY": "2004",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "53",
+                    "D": "6",
+                    "DDD": None,
+                },
+                datetime.date(2005, 1, 1),
+                5,
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = PythonTimeBuilder.build_date(**testtuple[0])
+            self.assertEqual(result, testtuple[1])
+            self.assertEqual(result.weekday(), testtuple[2])
+
+    def test_build_time(self):
+        testtuples = (
+            ({}, datetime.time()),
+            ({"hh": "12.5"}, datetime.time(hour=12, minute=30)),
+            (
+                {"hh": "23.99999999997"},
+                datetime.time(hour=23, minute=59, second=59, microsecond=999999),
+            ),
+            ({"hh": "1", "mm": "23"}, datetime.time(hour=1, minute=23)),
+            (
+                {"hh": "1", "mm": "23.4567"},
+                datetime.time(hour=1, minute=23, second=27, microsecond=402000),
+            ),
+            (
+                {"hh": "14", "mm": "43.999999997"},
+                datetime.time(hour=14, minute=43, second=59, microsecond=999999),
+            ),
+            (
+                {"hh": "1", "mm": "23", "ss": "45"},
+                datetime.time(hour=1, minute=23, second=45),
+            ),
+            (
+                {"hh": "23", "mm": "21", "ss": "28.512400"},
+                datetime.time(hour=23, minute=21, second=28, microsecond=512400),
+            ),
+            (
+                {"hh": "01", "mm": "03", "ss": "11.858714"},
+                datetime.time(hour=1, minute=3, second=11, microsecond=858714),
+            ),
+            (
+                {"hh": "14", "mm": "43", "ss": "59.9999997"},
+                datetime.time(hour=14, minute=43, second=59, microsecond=999999),
+            ),
+            ({"hh": "24"}, datetime.time(hour=0)),
+            ({"hh": "24", "mm": "00"}, datetime.time(hour=0)),
+            ({"hh": "24", "mm": "00", "ss": "00"}, datetime.time(hour=0)),
+            (
+                {"tz": TimezoneTuple(False, None, "00", "00", "UTC")},
+                datetime.time(tzinfo=UTCOffset(name="UTC", minutes=0)),
+            ),
+            (
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+                datetime.time(
+                    hour=23,
+                    minute=21,
+                    second=28,
+                    microsecond=512400,
+                    tzinfo=UTCOffset(name="+00:00", minutes=0),
+                ),
+            ),
+            (
+                {
+                    "hh": "1",
+                    "mm": "23",
+                    "tz": TimezoneTuple(False, None, "01", "00", "+1"),
+                },
+                datetime.time(
+                    hour=1, minute=23, tzinfo=UTCOffset(name="+1", minutes=60)
+                ),
+            ),
+            (
+                {
+                    "hh": "1",
+                    "mm": "23.4567",
+                    "tz": TimezoneTuple(True, None, "01", "00", "-1"),
+                },
+                datetime.time(
+                    hour=1,
+                    minute=23,
+                    second=27,
+                    microsecond=402000,
+                    tzinfo=UTCOffset(name="-1", minutes=-60),
+                ),
+            ),
+            (
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "01", "30", "+1:30"),
+                },
+                datetime.time(
+                    hour=23,
+                    minute=21,
+                    second=28,
+                    microsecond=512400,
+                    tzinfo=UTCOffset(name="+1:30", minutes=90),
+                ),
+            ),
+            (
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "11", "15", "+11:15"),
+                },
+                datetime.time(
+                    hour=23,
+                    minute=21,
+                    second=28,
+                    microsecond=512400,
+                    tzinfo=UTCOffset(name="+11:15", minutes=675),
+                ),
+            ),
+            (
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "12", "34", "+12:34"),
+                },
+                datetime.time(
+                    hour=23,
+                    minute=21,
+                    second=28,
+                    microsecond=512400,
+                    tzinfo=UTCOffset(name="+12:34", minutes=754),
+                ),
+            ),
+            (
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "00", "00", "UTC"),
+                },
+                datetime.time(
+                    hour=23,
+                    minute=21,
+                    second=28,
+                    microsecond=512400,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            # https://bitbucket.org/nielsenb/aniso8601/issues/21/sub-microsecond-precision-is-lost-when
+            (
+                {"hh": "14.9999999999999999"},
+                datetime.time(hour=14, minute=59, second=59, microsecond=999999),
+            ),
+            ({"mm": "0.00000000999"}, datetime.time()),
+            ({"mm": "0.0000000999"}, datetime.time(microsecond=5)),
+            ({"ss": "0.0000001"}, datetime.time()),
+            ({"ss": "2.0000048"}, datetime.time(second=2, microsecond=4)),
+        )
+
+        for testtuple in testtuples:
+            result = PythonTimeBuilder.build_time(**testtuple[0])
+            self.assertEqual(result, testtuple[1])
+
+    def test_build_datetime(self):
+        testtuples = (
+            (
+                (
+                    DateTuple("2019", "06", "05", None, None, None),
+                    TimeTuple("01", "03", "11.858714", None),
+                ),
+                datetime.datetime(
+                    2019, 6, 5, hour=1, minute=3, second=11, microsecond=858714
+                ),
+            ),
+            (
+                (
+                    DateTuple("1234", "02", "03", None, None, None),
+                    TimeTuple("23", "21", "28.512400", None),
+                ),
+                datetime.datetime(
+                    1234, 2, 3, hour=23, minute=21, second=28, microsecond=512400
+                ),
+            ),
+            (
+                (
+                    DateTuple("1981", "04", "05", None, None, None),
+                    TimeTuple(
+                        "23",
+                        "21",
+                        "28.512400",
+                        TimezoneTuple(False, None, "11", "15", "+11:15"),
+                    ),
+                ),
+                datetime.datetime(
+                    1981,
+                    4,
+                    5,
+                    hour=23,
+                    minute=21,
+                    second=28,
+                    microsecond=512400,
+                    tzinfo=UTCOffset(name="+11:15", minutes=675),
+                ),
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = PythonTimeBuilder.build_datetime(*testtuple[0])
+            self.assertEqual(result, testtuple[1])
+
+    def test_build_duration(self):
+        testtuples = (
+            (
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+                datetime.timedelta(days=428, hours=4, minutes=54, seconds=6),
+            ),
+            (
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+                datetime.timedelta(days=428, hours=4, minutes=54, seconds=6.5),
+            ),
+            ({"PnY": "1", "PnM": "2", "PnD": "3"}, datetime.timedelta(days=428)),
+            ({"PnY": "1", "PnM": "2", "PnD": "3.5"}, datetime.timedelta(days=428.5)),
+            (
+                {"TnH": "4", "TnM": "54", "TnS": "6.5"},
+                datetime.timedelta(hours=4, minutes=54, seconds=6.5),
+            ),
+            (
+                {"TnH": "1", "TnM": "3", "TnS": "11.858714"},
+                datetime.timedelta(hours=1, minutes=3, seconds=11, microseconds=858714),
+            ),
+            (
+                {"TnH": "4", "TnM": "54", "TnS": "28.512400"},
+                datetime.timedelta(
+                    hours=4, minutes=54, seconds=28, microseconds=512400
+                ),
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            # https://bitbucket.org/nielsenb/aniso8601/issues/21/sub-microsecond-precision-is-lost-when
+            (
+                {"PnY": "1999.9999999999999999"},
+                datetime.timedelta(days=729999, seconds=86399, microseconds=999999),
+            ),
+            (
+                {"PnM": "1.9999999999999999"},
+                datetime.timedelta(
+                    days=59, hours=23, minutes=59, seconds=59, microseconds=999999
+                ),
+            ),
+            (
+                {"PnW": "1.9999999999999999"},
+                datetime.timedelta(
+                    days=13, hours=23, minutes=59, seconds=59, microseconds=999999
+                ),
+            ),
+            (
+                {"PnD": "1.9999999999999999"},
+                datetime.timedelta(
+                    days=1, hours=23, minutes=59, seconds=59, microseconds=999999
+                ),
+            ),
+            (
+                {"TnH": "14.9999999999999999"},
+                datetime.timedelta(
+                    hours=14, minutes=59, seconds=59, microseconds=999999
+                ),
+            ),
+            ({"TnM": "0.00000000999"}, datetime.timedelta(0)),
+            ({"TnM": "0.0000000999"}, datetime.timedelta(microseconds=5)),
+            ({"TnS": "0.0000001"}, datetime.timedelta(0)),
+            ({"TnS": "2.0000048"}, datetime.timedelta(seconds=2, microseconds=4)),
+            ({"PnY": "1"}, datetime.timedelta(days=365)),
+            ({"PnY": "1.5"}, datetime.timedelta(days=547.5)),
+            ({"PnM": "1"}, datetime.timedelta(days=30)),
+            ({"PnM": "1.5"}, datetime.timedelta(days=45)),
+            ({"PnW": "1"}, datetime.timedelta(days=7)),
+            ({"PnW": "1.5"}, datetime.timedelta(days=10.5)),
+            ({"PnD": "1"}, datetime.timedelta(days=1)),
+            ({"PnD": "1.5"}, datetime.timedelta(days=1.5)),
+            (
+                {
+                    "PnY": "0003",
+                    "PnM": "06",
+                    "PnD": "04",
+                    "TnH": "12",
+                    "TnM": "30",
+                    "TnS": "05",
+                },
+                datetime.timedelta(days=1279, hours=12, minutes=30, seconds=5),
+            ),
+            (
+                {
+                    "PnY": "0003",
+                    "PnM": "06",
+                    "PnD": "04",
+                    "TnH": "12",
+                    "TnM": "30",
+                    "TnS": "05.5",
+                },
+                datetime.timedelta(days=1279, hours=12, minutes=30, seconds=5.5),
+            ),
+            # Test timedelta limit
+            (
+                {"PnD": "999999999", "TnH": "23", "TnM": "59", "TnS": "59.999999"},
+                datetime.timedelta.max,
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                {
+                    "PnY": "0001",
+                    "PnM": "02",
+                    "PnD": "03",
+                    "TnH": "14",
+                    "TnM": "43",
+                    "TnS": "59.9999997",
+                },
+                datetime.timedelta(
+                    days=428, hours=14, minutes=43, seconds=59, microseconds=999999
+                ),
+            ),
+            # Verify overflows
+            ({"TnH": "36"}, datetime.timedelta(days=1, hours=12)),
+        )
+
+        for testtuple in testtuples:
+            result = PythonTimeBuilder.build_duration(**testtuple[0])
+            self.assertEqual(result, testtuple[1])
+
+    def test_build_interval(self):
+        testtuples = (
+            (
+                {
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "duration": DurationTuple(None, "1", None, None, None, None, None),
+                },
+                datetime.datetime(year=1981, month=4, day=5, hour=1, minute=1),
+                datetime.datetime(year=1981, month=3, day=6, hour=1, minute=1),
+            ),
+            (
+                {
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                    "duration": DurationTuple(None, "1", None, None, None, None, None),
+                },
+                datetime.date(year=1981, month=4, day=5),
+                datetime.date(year=1981, month=3, day=6),
+            ),
+            (
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        "1.5", None, None, None, None, None, None
+                    ),
+                },
+                datetime.date(year=2018, month=3, day=6),
+                datetime.datetime(year=2016, month=9, day=4, hour=12),
+            ),
+            (
+                {
+                    "end": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "1", None, None),
+                },
+                datetime.date(year=2014, month=11, day=12),
+                datetime.datetime(year=2014, month=11, day=11, hour=23),
+            ),
+            (
+                {
+                    "end": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "4", "54", "6.5"),
+                },
+                datetime.date(year=2014, month=11, day=12),
+                datetime.datetime(
+                    year=2014,
+                    month=11,
+                    day=11,
+                    hour=19,
+                    minute=5,
+                    second=53,
+                    microsecond=500000,
+                ),
+            ),
+            (
+                {
+                    "end": DatetimeTuple(
+                        DateTuple("2050", "03", "01", None, None, None),
+                        TimeTuple(
+                            "13",
+                            "00",
+                            "00",
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "duration": DurationTuple(None, None, None, None, "10", None, None),
+                },
+                datetime.datetime(
+                    year=2050,
+                    month=3,
+                    day=1,
+                    hour=13,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+                datetime.datetime(
+                    year=2050,
+                    month=3,
+                    day=1,
+                    hour=3,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            # https://bitbucket.org/nielsenb/aniso8601/issues/21/sub-microsecond-precision-is-lost-when
+            (
+                {
+                    "end": DateTuple("2000", "01", "01", None, None, None),
+                    "duration": DurationTuple(
+                        "1999.9999999999999999", None, None, None, None, None, None
+                    ),
+                },
+                datetime.date(year=2000, month=1, day=1),
+                datetime.datetime(
+                    year=1, month=4, day=30, hour=0, minute=0, second=0, microsecond=1
+                ),
+            ),
+            (
+                {
+                    "end": DateTuple("1989", "03", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, "1.9999999999999999", None, None, None, None, None
+                    ),
+                },
+                datetime.date(year=1989, month=3, day=1),
+                datetime.datetime(
+                    year=1988,
+                    month=12,
+                    day=31,
+                    hour=0,
+                    minute=0,
+                    second=0,
+                    microsecond=1,
+                ),
+            ),
+            (
+                {
+                    "end": DateTuple("1989", "03", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, "1.9999999999999999", None, None, None, None
+                    ),
+                },
+                datetime.date(year=1989, month=3, day=1),
+                datetime.datetime(
+                    year=1989,
+                    month=2,
+                    day=15,
+                    hour=0,
+                    minute=0,
+                    second=0,
+                    microsecond=1,
+                ),
+            ),
+            (
+                {
+                    "end": DateTuple("1989", "03", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, "1.9999999999999999", None, None, None
+                    ),
+                },
+                datetime.date(year=1989, month=3, day=1),
+                datetime.datetime(
+                    year=1989,
+                    month=2,
+                    day=27,
+                    hour=0,
+                    minute=0,
+                    second=0,
+                    microsecond=1,
+                ),
+            ),
+            (
+                {
+                    "end": DateTuple("2001", "01", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, "14.9999999999999999", None, None
+                    ),
+                },
+                datetime.date(year=2001, month=1, day=1),
+                datetime.datetime(
+                    year=2000,
+                    month=12,
+                    day=31,
+                    hour=9,
+                    minute=0,
+                    second=0,
+                    microsecond=1,
+                ),
+            ),
+            (
+                {
+                    "end": DateTuple("2001", "01", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, "0.00000000999", None
+                    ),
+                },
+                datetime.date(year=2001, month=1, day=1),
+                datetime.datetime(year=2001, month=1, day=1),
+            ),
+            (
+                {
+                    "end": DateTuple("2001", "01", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, "0.0000000999", None
+                    ),
+                },
+                datetime.date(year=2001, month=1, day=1),
+                datetime.datetime(
+                    year=2000,
+                    month=12,
+                    day=31,
+                    hour=23,
+                    minute=59,
+                    second=59,
+                    microsecond=999995,
+                ),
+            ),
+            (
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "0.0000001"
+                    ),
+                },
+                datetime.date(year=2018, month=3, day=6),
+                datetime.datetime(year=2018, month=3, day=6),
+            ),
+            (
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "2.0000048"
+                    ),
+                },
+                datetime.date(year=2018, month=3, day=6),
+                datetime.datetime(
+                    year=2018,
+                    month=3,
+                    day=5,
+                    hour=23,
+                    minute=59,
+                    second=57,
+                    microsecond=999996,
+                ),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "duration": DurationTuple(None, "1", None, "1", None, "1", None),
+                },
+                datetime.datetime(year=1981, month=4, day=5, hour=1, minute=1),
+                datetime.datetime(year=1981, month=5, day=6, hour=1, minute=2),
+            ),
+            (
+                {
+                    "start": DateTuple("1981", "04", "05", None, None, None),
+                    "duration": DurationTuple(None, "1", None, "1", None, None, None),
+                },
+                datetime.date(year=1981, month=4, day=5),
+                datetime.date(year=1981, month=5, day=6),
+            ),
+            (
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, "2.5", None, None, None, None, None
+                    ),
+                },
+                datetime.date(year=2018, month=3, day=6),
+                datetime.date(year=2018, month=5, day=20),
+            ),
+            (
+                {
+                    "start": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "1", None, None),
+                },
+                datetime.date(year=2014, month=11, day=12),
+                datetime.datetime(year=2014, month=11, day=12, hour=1, minute=0),
+            ),
+            (
+                {
+                    "start": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "4", "54", "6.5"),
+                },
+                datetime.date(year=2014, month=11, day=12),
+                datetime.datetime(
+                    year=2014,
+                    month=11,
+                    day=12,
+                    hour=4,
+                    minute=54,
+                    second=6,
+                    microsecond=500000,
+                ),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2050", "03", "01", None, None, None),
+                        TimeTuple(
+                            "13",
+                            "00",
+                            "00",
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "duration": DurationTuple(None, None, None, None, "10", None, None),
+                },
+                datetime.datetime(
+                    year=2050,
+                    month=3,
+                    day=1,
+                    hour=13,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+                datetime.datetime(
+                    year=2050,
+                    month=3,
+                    day=1,
+                    hour=23,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                {
+                    "start": DateTuple("0001", "01", "01", None, None, None),
+                    "duration": DurationTuple(
+                        "1999.9999999999999999", None, None, None, None, None, None
+                    ),
+                },
+                datetime.date(year=1, month=1, day=1),
+                datetime.datetime(
+                    year=1999,
+                    month=9,
+                    day=3,
+                    hour=23,
+                    minute=59,
+                    second=59,
+                    microsecond=999999,
+                ),
+            ),
+            (
+                {
+                    "start": DateTuple("1989", "03", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, "1.9999999999999999", None, None, None, None, None
+                    ),
+                },
+                datetime.date(year=1989, month=3, day=1),
+                datetime.datetime(
+                    year=1989,
+                    month=4,
+                    day=29,
+                    hour=23,
+                    minute=59,
+                    second=59,
+                    microsecond=999999,
+                ),
+            ),
+            (
+                {
+                    "start": DateTuple("1989", "03", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, "1.9999999999999999", None, None, None, None
+                    ),
+                },
+                datetime.date(year=1989, month=3, day=1),
+                datetime.datetime(
+                    year=1989,
+                    month=3,
+                    day=14,
+                    hour=23,
+                    minute=59,
+                    second=59,
+                    microsecond=999999,
+                ),
+            ),
+            (
+                {
+                    "start": DateTuple("1989", "03", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, "1.9999999999999999", None, None, None
+                    ),
+                },
+                datetime.date(year=1989, month=3, day=1),
+                datetime.datetime(
+                    year=1989,
+                    month=3,
+                    day=2,
+                    hour=23,
+                    minute=59,
+                    second=59,
+                    microsecond=999999,
+                ),
+            ),
+            (
+                {
+                    "start": DateTuple("2001", "01", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, "14.9999999999999999", None, None
+                    ),
+                },
+                datetime.date(year=2001, month=1, day=1),
+                datetime.datetime(
+                    year=2001,
+                    month=1,
+                    day=1,
+                    hour=14,
+                    minute=59,
+                    second=59,
+                    microsecond=999999,
+                ),
+            ),
+            (
+                {
+                    "start": DateTuple("2001", "01", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, "0.00000000999", None
+                    ),
+                },
+                datetime.date(year=2001, month=1, day=1),
+                datetime.datetime(year=2001, month=1, day=1),
+            ),
+            (
+                {
+                    "start": DateTuple("2001", "01", "01", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, "0.0000000999", None
+                    ),
+                },
+                datetime.date(year=2001, month=1, day=1),
+                datetime.datetime(
+                    year=2001, month=1, day=1, hour=0, minute=0, second=0, microsecond=5
+                ),
+            ),
+            (
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "0.0000001"
+                    ),
+                },
+                datetime.date(year=2018, month=3, day=6),
+                datetime.datetime(year=2018, month=3, day=6),
+            ),
+            (
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "2.0000048"
+                    ),
+                },
+                datetime.date(year=2018, month=3, day=6),
+                datetime.datetime(
+                    year=2018, month=3, day=6, hour=0, minute=0, second=2, microsecond=4
+                ),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                },
+                datetime.datetime(year=1980, month=3, day=5, hour=1, minute=1),
+                datetime.datetime(year=1981, month=4, day=5, hour=1, minute=1),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                },
+                datetime.datetime(year=1980, month=3, day=5, hour=1, minute=1),
+                datetime.date(year=1981, month=4, day=5),
+            ),
+            (
+                {
+                    "start": DateTuple("1980", "03", "05", None, None, None),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                },
+                datetime.date(year=1980, month=3, day=5),
+                datetime.datetime(year=1981, month=4, day=5, hour=1, minute=1),
+            ),
+            (
+                {
+                    "start": DateTuple("1980", "03", "05", None, None, None),
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                },
+                datetime.date(year=1980, month=3, day=5),
+                datetime.date(year=1981, month=4, day=5),
+            ),
+            (
+                {
+                    "start": DateTuple("1981", "04", "05", None, None, None),
+                    "end": DateTuple("1980", "03", "05", None, None, None),
+                },
+                datetime.date(year=1981, month=4, day=5),
+                datetime.date(year=1980, month=3, day=5),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2050", "03", "01", None, None, None),
+                        TimeTuple(
+                            "13",
+                            "00",
+                            "00",
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("2050", "05", "11", None, None, None),
+                        TimeTuple(
+                            "15",
+                            "30",
+                            "00",
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                },
+                datetime.datetime(
+                    year=2050,
+                    month=3,
+                    day=1,
+                    hour=13,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+                datetime.datetime(
+                    year=2050,
+                    month=5,
+                    day=11,
+                    hour=15,
+                    minute=30,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+            ),
+            # Test concise representation
+            (
+                {
+                    "start": DateTuple("2020", "01", "01", None, None, None),
+                    "end": DateTuple(None, None, "02", None, None, None),
+                },
+                datetime.date(year=2020, month=1, day=1),
+                datetime.date(year=2020, month=1, day=2),
+            ),
+            (
+                {
+                    "start": DateTuple("2008", "02", "15", None, None, None),
+                    "end": DateTuple(None, "03", "14", None, None, None),
+                },
+                datetime.date(year=2008, month=2, day=15),
+                datetime.date(year=2008, month=3, day=14),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "12", "14", None, None, None),
+                        TimeTuple("13", "30", None, None),
+                    ),
+                    "end": TimeTuple("15", "30", None, None),
+                },
+                datetime.datetime(year=2007, month=12, day=14, hour=13, minute=30),
+                datetime.datetime(year=2007, month=12, day=14, hour=15, minute=30),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("09", "00", None, None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "15", None, None, None),
+                        TimeTuple("17", "00", None, None),
+                    ),
+                },
+                datetime.datetime(year=2007, month=11, day=13, hour=9),
+                datetime.datetime(year=2007, month=11, day=15, hour=17),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("00", "00", None, None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "16", None, None, None),
+                        TimeTuple("00", "00", None, None),
+                    ),
+                },
+                datetime.datetime(year=2007, month=11, day=13),
+                datetime.datetime(year=2007, month=11, day=16),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple(
+                            "09",
+                            "00",
+                            None,
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "15", None, None, None),
+                        TimeTuple("17", "00", None, None),
+                    ),
+                },
+                datetime.datetime(
+                    year=2007,
+                    month=11,
+                    day=13,
+                    hour=9,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+                datetime.datetime(
+                    year=2007,
+                    month=11,
+                    day=15,
+                    hour=17,
+                    tzinfo=UTCOffset(name="UTC", minutes=0),
+                ),
+            ),
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("09", "00", None, None),
+                    ),
+                    "end": TimeTuple("12", "34.567", None, None),
+                },
+                datetime.datetime(year=2007, month=11, day=13, hour=9),
+                datetime.datetime(
+                    year=2007,
+                    month=11,
+                    day=13,
+                    hour=12,
+                    minute=34,
+                    second=34,
+                    microsecond=20000,
+                ),
+            ),
+            (
+                {
+                    "start": DateTuple("2007", "11", "13", None, None, None),
+                    "end": TimeTuple("12", "34", None, None),
+                },
+                datetime.date(year=2007, month=11, day=13),
+                datetime.datetime(year=2007, month=11, day=13, hour=12, minute=34),
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00.0000001", None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("14", "43", "59.9999997", None),
+                    ),
+                },
+                datetime.datetime(year=1980, month=3, day=5, hour=1, minute=1),
+                datetime.datetime(
+                    year=1981,
+                    month=4,
+                    day=5,
+                    hour=14,
+                    minute=43,
+                    second=59,
+                    microsecond=999999,
+                ),
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = PythonTimeBuilder.build_interval(**testtuple[0])
+            self.assertEqual(result[0], testtuple[1])
+            self.assertEqual(result[1], testtuple[2])
+
+    def test_build_repeating_interval(self):
+        args = {
+            "Rnn": "3",
+            "interval": IntervalTuple(
+                DateTuple("1981", "04", "05", None, None, None),
+                None,
+                DurationTuple(None, None, None, "1", None, None, None),
+            ),
+        }
+        results = list(PythonTimeBuilder.build_repeating_interval(**args))
+
+        self.assertEqual(results[0], datetime.date(year=1981, month=4, day=5))
+        self.assertEqual(results[1], datetime.date(year=1981, month=4, day=6))
+        self.assertEqual(results[2], datetime.date(year=1981, month=4, day=7))
+
+        args = {
+            "Rnn": "11",
+            "interval": IntervalTuple(
+                None,
+                DatetimeTuple(
+                    DateTuple("1980", "03", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                DurationTuple(None, None, None, None, "1", "2", None),
+            ),
+        }
+        results = list(PythonTimeBuilder.build_repeating_interval(**args))
+
+        for dateindex in compat.range(0, 11):
+            self.assertEqual(
+                results[dateindex],
+                datetime.datetime(year=1980, month=3, day=5, hour=1, minute=1)
+                - dateindex * datetime.timedelta(hours=1, minutes=2),
+            )
+
+        args = {
+            "Rnn": "2",
+            "interval": IntervalTuple(
+                DatetimeTuple(
+                    DateTuple("1980", "03", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                DatetimeTuple(
+                    DateTuple("1981", "04", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                None,
+            ),
+        }
+        results = list(PythonTimeBuilder.build_repeating_interval(**args))
+
+        self.assertEqual(
+            results[0], datetime.datetime(year=1980, month=3, day=5, hour=1, minute=1)
+        )
+        self.assertEqual(
+            results[1], datetime.datetime(year=1981, month=4, day=5, hour=1, minute=1)
+        )
+
+        args = {
+            "Rnn": "2",
+            "interval": IntervalTuple(
+                DatetimeTuple(
+                    DateTuple("1980", "03", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                DatetimeTuple(
+                    DateTuple("1981", "04", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                None,
+            ),
+        }
+        results = list(PythonTimeBuilder.build_repeating_interval(**args))
+
+        self.assertEqual(
+            results[0], datetime.datetime(year=1980, month=3, day=5, hour=1, minute=1)
+        )
+        self.assertEqual(
+            results[1], datetime.datetime(year=1981, month=4, day=5, hour=1, minute=1)
+        )
+
+        args = {
+            "R": True,
+            "interval": IntervalTuple(
+                None,
+                DatetimeTuple(
+                    DateTuple("1980", "03", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                DurationTuple(None, None, None, None, "1", "2", None),
+            ),
+        }
+        resultgenerator = PythonTimeBuilder.build_repeating_interval(**args)
+
+        # Test the first 11 generated
+        for dateindex in compat.range(0, 11):
+            self.assertEqual(
+                next(resultgenerator),
+                datetime.datetime(year=1980, month=3, day=5, hour=1, minute=1)
+                - dateindex * datetime.timedelta(hours=1, minutes=2),
+            )
+
+        args = {
+            "R": True,
+            "interval": IntervalTuple(
+                DateTuple("1981", "04", "05", None, None, None),
+                None,
+                DurationTuple(None, None, None, "1", None, None, None),
+            ),
+        }
+        resultgenerator = PythonTimeBuilder.build_repeating_interval(**args)
+
+        # Test the first 11 generated
+        for dateindex in compat.range(0, 11):
+            self.assertEqual(
+                next(resultgenerator),
+                (
+                    datetime.datetime(year=1981, month=4, day=5, hour=0, minute=0)
+                    + dateindex * datetime.timedelta(days=1)
+                ).date(),
+            )
+
+    def test_build_timezone(self):
+        testtuples = (
+            ({"Z": True, "name": "Z"}, datetime.timedelta(hours=0), "UTC"),
+            (
+                {"negative": False, "hh": "00", "mm": "00", "name": "+00:00"},
+                datetime.timedelta(hours=0),
+                "+00:00",
+            ),
+            (
+                {"negative": False, "hh": "01", "mm": "00", "name": "+01:00"},
+                datetime.timedelta(hours=1),
+                "+01:00",
+            ),
+            (
+                {"negative": True, "hh": "01", "mm": "00", "name": "-01:00"},
+                -datetime.timedelta(hours=1),
+                "-01:00",
+            ),
+            (
+                {"negative": False, "hh": "00", "mm": "12", "name": "+00:12"},
+                datetime.timedelta(minutes=12),
+                "+00:12",
+            ),
+            (
+                {"negative": False, "hh": "01", "mm": "23", "name": "+01:23"},
+                datetime.timedelta(hours=1, minutes=23),
+                "+01:23",
+            ),
+            (
+                {"negative": True, "hh": "01", "mm": "23", "name": "-01:23"},
+                -datetime.timedelta(hours=1, minutes=23),
+                "-01:23",
+            ),
+            (
+                {"negative": False, "hh": "00", "name": "+00"},
+                datetime.timedelta(hours=0),
+                "+00",
+            ),
+            (
+                {"negative": False, "hh": "01", "name": "+01"},
+                datetime.timedelta(hours=1),
+                "+01",
+            ),
+            (
+                {"negative": True, "hh": "01", "name": "-01"},
+                -datetime.timedelta(hours=1),
+                "-01",
+            ),
+            (
+                {"negative": False, "hh": "12", "name": "+12"},
+                datetime.timedelta(hours=12),
+                "+12",
+            ),
+            (
+                {"negative": True, "hh": "12", "name": "-12"},
+                -datetime.timedelta(hours=12),
+                "-12",
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = PythonTimeBuilder.build_timezone(**testtuple[0])
+            self.assertEqual(result.utcoffset(None), testtuple[1])
+            self.assertEqual(result.tzname(None), testtuple[2])
+
+    def test_range_check_date(self):
+        # 0 isn't a valid year for a Python builder
+        with self.assertRaises(YearOutOfBoundsError):
+            PythonTimeBuilder.build_date(YYYY="0000")
+
+        # Leap year
+        # https://bitbucket.org/nielsenb/aniso8601/issues/14/parsing-ordinal-dates-should-only-allow
+        with self.assertRaises(DayOutOfBoundsError):
+            PythonTimeBuilder.build_date(YYYY="1981", DDD="366")
+
+    def test_range_check_time(self):
+        # Hour 24 can only represent midnight
+        with self.assertRaises(MidnightBoundsError):
+            PythonTimeBuilder.build_time(hh="24", mm="00", ss="01")
+
+        with self.assertRaises(MidnightBoundsError):
+            PythonTimeBuilder.build_time(hh="24", mm="00.1")
+
+        with self.assertRaises(MidnightBoundsError):
+            PythonTimeBuilder.build_time(hh="24", mm="01")
+
+        with self.assertRaises(MidnightBoundsError):
+            PythonTimeBuilder.build_time(hh="24.1")
+
+    def test_range_check_duration(self):
+        with self.assertRaises(YearOutOfBoundsError):
+            PythonTimeBuilder.build_duration(
+                PnY=str((datetime.timedelta.max.days // 365) + 1)
+            )
+
+        with self.assertRaises(MonthOutOfBoundsError):
+            PythonTimeBuilder.build_duration(
+                PnM=str((datetime.timedelta.max.days // 30) + 1)
+            )
+
+        with self.assertRaises(DayOutOfBoundsError):
+            PythonTimeBuilder.build_duration(PnD=str(datetime.timedelta.max.days + 1))
+
+        with self.assertRaises(WeekOutOfBoundsError):
+            PythonTimeBuilder.build_duration(
+                PnW=str((datetime.timedelta.max.days // 7) + 1)
+            )
+
+        with self.assertRaises(HoursOutOfBoundsError):
+            PythonTimeBuilder.build_duration(
+                TnH=str((datetime.timedelta.max.days * 24) + 24)
+            )
+
+        with self.assertRaises(MinutesOutOfBoundsError):
+            PythonTimeBuilder.build_duration(
+                TnM=str((datetime.timedelta.max.days * 24 * 60) + 24 * 60)
+            )
+
+        with self.assertRaises(SecondsOutOfBoundsError):
+            PythonTimeBuilder.build_duration(
+                TnS=str((datetime.timedelta.max.days * 24 * 60 * 60) + 24 * 60 * 60)
+            )
+
+        # Split max range across all parts
+        maxpart = datetime.timedelta.max.days // 7
+
+        with self.assertRaises(DayOutOfBoundsError):
+            PythonTimeBuilder.build_duration(
+                PnY=str((maxpart // 365) + 1),
+                PnM=str((maxpart // 30) + 1),
+                PnD=str((maxpart + 1)),
+                PnW=str((maxpart // 7) + 1),
+                TnH=str((maxpart * 24) + 1),
+                TnM=str((maxpart * 24 * 60) + 1),
+                TnS=str((maxpart * 24 * 60 * 60) + 1),
+            )
+
+    def test_range_check_interval(self):
+        with self.assertRaises(YearOutOfBoundsError):
+            PythonTimeBuilder.build_interval(
+                start=DateTuple("0007", None, None, None, None, None),
+                duration=DurationTuple(
+                    None, None, None, str(datetime.timedelta.max.days), None, None, None
+                ),
+            )
+
+        with self.assertRaises(YearOutOfBoundsError):
+            PythonTimeBuilder.build_interval(
+                start=DatetimeTuple(
+                    DateTuple("0007", None, None, None, None, None),
+                    TimeTuple("1", None, None, None),
+                ),
+                duration=DurationTuple(
+                    str(datetime.timedelta.max.days // 365),
+                    None,
+                    None,
+                    None,
+                    None,
+                    None,
+                    None,
+                ),
+            )
+
+        with self.assertRaises(YearOutOfBoundsError):
+            PythonTimeBuilder.build_interval(
+                end=DateTuple("0001", None, None, None, None, None),
+                duration=DurationTuple("3", None, None, None, None, None, None),
+            )
+
+        with self.assertRaises(YearOutOfBoundsError):
+            PythonTimeBuilder.build_interval(
+                end=DatetimeTuple(
+                    DateTuple("0001", None, None, None, None, None),
+                    TimeTuple("1", None, None, None),
+                ),
+                duration=DurationTuple("2", None, None, None, None, None, None),
+            )
+
+    def test_build_week_date(self):
+        weekdate = PythonTimeBuilder._build_week_date(2009, 1)
+        self.assertEqual(weekdate, datetime.date(year=2008, month=12, day=29))
+
+        weekdate = PythonTimeBuilder._build_week_date(2009, 53, isoday=7)
+        self.assertEqual(weekdate, datetime.date(year=2010, month=1, day=3))
+
+    def test_build_ordinal_date(self):
+        ordinaldate = PythonTimeBuilder._build_ordinal_date(1981, 95)
+        self.assertEqual(ordinaldate, datetime.date(year=1981, month=4, day=5))
+
+    def test_iso_year_start(self):
+        yearstart = PythonTimeBuilder._iso_year_start(2004)
+        self.assertEqual(yearstart, datetime.date(year=2003, month=12, day=29))
+
+        yearstart = PythonTimeBuilder._iso_year_start(2010)
+        self.assertEqual(yearstart, datetime.date(year=2010, month=1, day=4))
+
+        yearstart = PythonTimeBuilder._iso_year_start(2009)
+        self.assertEqual(yearstart, datetime.date(year=2008, month=12, day=29))
+
+    def test_date_generator(self):
+        startdate = datetime.date(year=2018, month=8, day=29)
+        timedelta = datetime.timedelta(days=1)
+        iterations = 10
+
+        generator = PythonTimeBuilder._date_generator(startdate, timedelta, iterations)
+
+        results = list(generator)
+
+        for dateindex in compat.range(0, 10):
+            self.assertEqual(
+                results[dateindex],
+                datetime.date(year=2018, month=8, day=29)
+                + dateindex * datetime.timedelta(days=1),
+            )
+
+    def test_date_generator_unbounded(self):
+        startdate = datetime.date(year=2018, month=8, day=29)
+        timedelta = datetime.timedelta(days=5)
+
+        generator = PythonTimeBuilder._date_generator_unbounded(startdate, timedelta)
+
+        # Check the first 10 results
+        for dateindex in compat.range(0, 10):
+            self.assertEqual(
+                next(generator),
+                datetime.date(year=2018, month=8, day=29)
+                + dateindex * datetime.timedelta(days=5),
+            )
+
+    def test_distribute_microseconds(self):
+        self.assertEqual(PythonTimeBuilder._distribute_microseconds(1, (), ()), (1,))
+        self.assertEqual(
+            PythonTimeBuilder._distribute_microseconds(11, (0,), (10,)), (1, 1)
+        )
+        self.assertEqual(
+            PythonTimeBuilder._distribute_microseconds(211, (0, 0), (100, 10)),
+            (2, 1, 1),
+        )
+
+        self.assertEqual(PythonTimeBuilder._distribute_microseconds(1, (), ()), (1,))
+        self.assertEqual(
+            PythonTimeBuilder._distribute_microseconds(11, (5,), (10,)), (6, 1)
+        )
+        self.assertEqual(
+            PythonTimeBuilder._distribute_microseconds(211, (10, 5), (100, 10)),
+            (12, 6, 1),
+        )
diff --git a/libs/aniso8601/compat.py b/libs/aniso8601/compat.py
new file mode 100644
index 000000000..25af5794a
--- /dev/null
+++ b/libs/aniso8601/compat.py
@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import sys
+
+PY2 = sys.version_info[0] == 2
+
+if PY2:  # pragma: no cover
+    range = xrange  # pylint: disable=undefined-variable
+else:
+    range = range
+
+
+def is_string(tocheck):
+    # pylint: disable=undefined-variable
+    if PY2:  # pragma: no cover
+        return isinstance(tocheck, str) or isinstance(tocheck, unicode)
+
+    return isinstance(tocheck, str)
diff --git a/libs/aniso8601/date.py b/libs/aniso8601/date.py
new file mode 100644
index 000000000..ea0cf9c59
--- /dev/null
+++ b/libs/aniso8601/date.py
@@ -0,0 +1,161 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+from aniso8601.builders import TupleBuilder
+from aniso8601.builders.python import PythonTimeBuilder
+from aniso8601.compat import is_string
+from aniso8601.exceptions import ISOFormatError
+from aniso8601.resolution import DateResolution
+
+
+def get_date_resolution(isodatestr):
+    # Valid string formats are:
+    #
+    # Y[YYY]
+    # YYYY-MM-DD
+    # YYYYMMDD
+    # YYYY-MM
+    # YYYY-Www
+    # YYYYWww
+    # YYYY-Www-D
+    # YYYYWwwD
+    # YYYY-DDD
+    # YYYYDDD
+    isodatetuple = parse_date(isodatestr, builder=TupleBuilder)
+
+    if isodatetuple.DDD is not None:
+        # YYYY-DDD
+        # YYYYDDD
+        return DateResolution.Ordinal
+
+    if isodatetuple.D is not None:
+        # YYYY-Www-D
+        # YYYYWwwD
+        return DateResolution.Weekday
+
+    if isodatetuple.Www is not None:
+        # YYYY-Www
+        # YYYYWww
+        return DateResolution.Week
+
+    if isodatetuple.DD is not None:
+        # YYYY-MM-DD
+        # YYYYMMDD
+        return DateResolution.Day
+
+    if isodatetuple.MM is not None:
+        # YYYY-MM
+        return DateResolution.Month
+
+    # Y[YYY]
+    return DateResolution.Year
+
+
+def parse_date(isodatestr, builder=PythonTimeBuilder):
+    # Given a string in any ISO 8601 date format, return a datetime.date
+    # object that corresponds to the given date. Valid string formats are:
+    #
+    # Y[YYY]
+    # YYYY-MM-DD
+    # YYYYMMDD
+    # YYYY-MM
+    # YYYY-Www
+    # YYYYWww
+    # YYYY-Www-D
+    # YYYYWwwD
+    # YYYY-DDD
+    # YYYYDDD
+    if is_string(isodatestr) is False:
+        raise ValueError("Date must be string.")
+
+    if isodatestr.startswith("+") or isodatestr.startswith("-"):
+        raise NotImplementedError(
+            "ISO 8601 extended year representation " "not supported."
+        )
+
+    if len(isodatestr) == 0 or isodatestr.count("-") > 2:
+        raise ISOFormatError('"{0}" is not a valid ISO 8601 date.'.format(isodatestr))
+    yearstr = None
+    monthstr = None
+    daystr = None
+    weekstr = None
+    weekdaystr = None
+    ordinaldaystr = None
+
+    if len(isodatestr) <= 4:
+        # Y[YYY]
+        yearstr = isodatestr
+    elif "W" in isodatestr:
+        if len(isodatestr) == 10:
+            # YYYY-Www-D
+            yearstr = isodatestr[0:4]
+            weekstr = isodatestr[6:8]
+            weekdaystr = isodatestr[9]
+        elif len(isodatestr) == 8:
+            if "-" in isodatestr:
+                # YYYY-Www
+                yearstr = isodatestr[0:4]
+                weekstr = isodatestr[6:]
+            else:
+                # YYYYWwwD
+                yearstr = isodatestr[0:4]
+                weekstr = isodatestr[5:7]
+                weekdaystr = isodatestr[7]
+        elif len(isodatestr) == 7:
+            # YYYYWww
+            yearstr = isodatestr[0:4]
+            weekstr = isodatestr[5:]
+    elif len(isodatestr) == 7:
+        if "-" in isodatestr:
+            # YYYY-MM
+            yearstr = isodatestr[0:4]
+            monthstr = isodatestr[5:]
+        else:
+            # YYYYDDD
+            yearstr = isodatestr[0:4]
+            ordinaldaystr = isodatestr[4:]
+    elif len(isodatestr) == 8:
+        if "-" in isodatestr:
+            # YYYY-DDD
+            yearstr = isodatestr[0:4]
+            ordinaldaystr = isodatestr[5:]
+        else:
+            # YYYYMMDD
+            yearstr = isodatestr[0:4]
+            monthstr = isodatestr[4:6]
+            daystr = isodatestr[6:]
+    elif len(isodatestr) == 10:
+        # YYYY-MM-DD
+        yearstr = isodatestr[0:4]
+        monthstr = isodatestr[5:7]
+        daystr = isodatestr[8:]
+    else:
+        raise ISOFormatError('"{0}" is not a valid ISO 8601 date.'.format(isodatestr))
+
+    hascomponent = False
+
+    for componentstr in [yearstr, monthstr, daystr, weekstr, weekdaystr, ordinaldaystr]:
+        if componentstr is not None:
+            hascomponent = True
+
+            if componentstr.isdigit() is False:
+                raise ISOFormatError(
+                    '"{0}" is not a valid ISO 8601 date.'.format(isodatestr)
+                )
+
+    if hascomponent is False:
+        raise ISOFormatError('"{0}" is not a valid ISO 8601 date.'.format(isodatestr))
+
+    return builder.build_date(
+        YYYY=yearstr,
+        MM=monthstr,
+        DD=daystr,
+        Www=weekstr,
+        D=weekdaystr,
+        DDD=ordinaldaystr,
+    )
diff --git a/libs/aniso8601/decimalfraction.py b/libs/aniso8601/decimalfraction.py
new file mode 100644
index 000000000..3086ee794
--- /dev/null
+++ b/libs/aniso8601/decimalfraction.py
@@ -0,0 +1,12 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+
+def normalize(value):
+    """Returns the string with decimal separators normalized."""
+    return value.replace(",", ".")
diff --git a/libs/aniso8601/duration.py b/libs/aniso8601/duration.py
new file mode 100644
index 000000000..cdc0f8f7f
--- /dev/null
+++ b/libs/aniso8601/duration.py
@@ -0,0 +1,291 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+from aniso8601 import compat
+from aniso8601.builders import TupleBuilder
+from aniso8601.builders.python import PythonTimeBuilder
+from aniso8601.date import parse_date
+from aniso8601.decimalfraction import normalize
+from aniso8601.exceptions import ISOFormatError
+from aniso8601.resolution import DurationResolution
+from aniso8601.time import parse_time
+
+
+def get_duration_resolution(isodurationstr):
+    # Valid string formats are:
+    #
+    # PnYnMnDTnHnMnS (or any reduced precision equivalent)
+    # PnW
+    # P<date>T<time>
+    isodurationtuple = parse_duration(isodurationstr, builder=TupleBuilder)
+
+    if isodurationtuple.TnS is not None:
+        return DurationResolution.Seconds
+
+    if isodurationtuple.TnM is not None:
+        return DurationResolution.Minutes
+
+    if isodurationtuple.TnH is not None:
+        return DurationResolution.Hours
+
+    if isodurationtuple.PnD is not None:
+        return DurationResolution.Days
+
+    if isodurationtuple.PnW is not None:
+        return DurationResolution.Weeks
+
+    if isodurationtuple.PnM is not None:
+        return DurationResolution.Months
+
+    return DurationResolution.Years
+
+
+def parse_duration(isodurationstr, builder=PythonTimeBuilder):
+    # Given a string representing an ISO 8601 duration, return a
+    # a duration built by the given builder. Valid formats are:
+    #
+    # PnYnMnDTnHnMnS (or any reduced precision equivalent)
+    # PnW
+    # P<date>T<time>
+
+    if compat.is_string(isodurationstr) is False:
+        raise ValueError("Duration must be string.")
+
+    if len(isodurationstr) == 0:
+        raise ISOFormatError(
+            '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
+        )
+
+    if isodurationstr[0] != "P":
+        raise ISOFormatError("ISO 8601 duration must start with a P.")
+
+    # If Y, M, D, H, S, or W are in the string,
+    # assume it is a specified duration
+    if _has_any_component(isodurationstr, ["Y", "M", "D", "H", "S", "W"]) is True:
+        parseresult = _parse_duration_prescribed(isodurationstr)
+        return builder.build_duration(**parseresult)
+
+    if isodurationstr.find("T") != -1:
+        parseresult = _parse_duration_combined(isodurationstr)
+        return builder.build_duration(**parseresult)
+
+    raise ISOFormatError(
+        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
+    )
+
+
+def _parse_duration_prescribed(isodurationstr):
+    # durationstr can be of the form PnYnMnDTnHnMnS or PnW
+
+    # Make sure the end character is valid
+    # https://bitbucket.org/nielsenb/aniso8601/issues/9/durations-with-trailing-garbage-are-parsed
+    if isodurationstr[-1] not in ["Y", "M", "D", "H", "S", "W"]:
+        raise ISOFormatError("ISO 8601 duration must end with a valid " "character.")
+
+    # Make sure only the lowest order element has decimal precision
+    durationstr = normalize(isodurationstr)
+
+    if durationstr.count(".") > 1:
+        raise ISOFormatError(
+            "ISO 8601 allows only lowest order element to " "have a decimal fraction."
+        )
+
+    seperatoridx = durationstr.find(".")
+
+    if seperatoridx != -1:
+        remaining = durationstr[seperatoridx + 1 : -1]
+
+        # There should only ever be 1 letter after a decimal if there is more
+        # then one, the string is invalid
+        if remaining.isdigit() is False:
+            raise ISOFormatError(
+                "ISO 8601 duration must end with " "a single valid character."
+            )
+
+    # Do not allow W in combination with other designators
+    # https://bitbucket.org/nielsenb/aniso8601/issues/2/week-designators-should-not-be-combinable
+    if (
+        durationstr.find("W") != -1
+        and _has_any_component(durationstr, ["Y", "M", "D", "H", "S"]) is True
+    ):
+        raise ISOFormatError(
+            "ISO 8601 week designators may not be combined "
+            "with other time designators."
+        )
+
+    # Parse the elements of the duration
+    if durationstr.find("T") == -1:
+        return _parse_duration_prescribed_notime(durationstr)
+
+    return _parse_duration_prescribed_time(durationstr)
+
+
+def _parse_duration_prescribed_notime(isodurationstr):
+    # durationstr can be of the form PnYnMnD or PnW
+
+    durationstr = normalize(isodurationstr)
+
+    yearstr = None
+    monthstr = None
+    daystr = None
+    weekstr = None
+
+    weekidx = durationstr.find("W")
+    yearidx = durationstr.find("Y")
+    monthidx = durationstr.find("M")
+    dayidx = durationstr.find("D")
+
+    if weekidx != -1:
+        weekstr = durationstr[1:-1]
+    elif yearidx != -1 and monthidx != -1 and dayidx != -1:
+        yearstr = durationstr[1:yearidx]
+        monthstr = durationstr[yearidx + 1 : monthidx]
+        daystr = durationstr[monthidx + 1 : -1]
+    elif yearidx != -1 and monthidx != -1:
+        yearstr = durationstr[1:yearidx]
+        monthstr = durationstr[yearidx + 1 : monthidx]
+    elif yearidx != -1 and dayidx != -1:
+        yearstr = durationstr[1:yearidx]
+        daystr = durationstr[yearidx + 1 : dayidx]
+    elif monthidx != -1 and dayidx != -1:
+        monthstr = durationstr[1:monthidx]
+        daystr = durationstr[monthidx + 1 : -1]
+    elif yearidx != -1:
+        yearstr = durationstr[1:-1]
+    elif monthidx != -1:
+        monthstr = durationstr[1:-1]
+    elif dayidx != -1:
+        daystr = durationstr[1:-1]
+    else:
+        raise ISOFormatError(
+            '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
+        )
+
+    for componentstr in [yearstr, monthstr, daystr, weekstr]:
+        if componentstr is not None:
+            if "." in componentstr:
+                intstr, fractionalstr = componentstr.split(".", 1)
+
+                if intstr.isdigit() is False:
+                    raise ISOFormatError(
+                        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
+                    )
+            else:
+                if componentstr.isdigit() is False:
+                    raise ISOFormatError(
+                        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
+                    )
+
+    return {"PnY": yearstr, "PnM": monthstr, "PnW": weekstr, "PnD": daystr}
+
+
+def _parse_duration_prescribed_time(isodurationstr):
+    # durationstr can be of the form PnYnMnDTnHnMnS
+
+    timeidx = isodurationstr.find("T")
+
+    datestr = isodurationstr[:timeidx]
+    timestr = normalize(isodurationstr[timeidx + 1 :])
+
+    hourstr = None
+    minutestr = None
+    secondstr = None
+
+    houridx = timestr.find("H")
+    minuteidx = timestr.find("M")
+    secondidx = timestr.find("S")
+
+    if houridx != -1 and minuteidx != -1 and secondidx != -1:
+        hourstr = timestr[0:houridx]
+        minutestr = timestr[houridx + 1 : minuteidx]
+        secondstr = timestr[minuteidx + 1 : -1]
+    elif houridx != -1 and minuteidx != -1:
+        hourstr = timestr[0:houridx]
+        minutestr = timestr[houridx + 1 : minuteidx]
+    elif houridx != -1 and secondidx != -1:
+        hourstr = timestr[0:houridx]
+        secondstr = timestr[houridx + 1 : -1]
+    elif minuteidx != -1 and secondidx != -1:
+        minutestr = timestr[0:minuteidx]
+        secondstr = timestr[minuteidx + 1 : -1]
+    elif houridx != -1:
+        hourstr = timestr[0:-1]
+    elif minuteidx != -1:
+        minutestr = timestr[0:-1]
+    elif secondidx != -1:
+        secondstr = timestr[0:-1]
+    else:
+        raise ISOFormatError(
+            '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
+        )
+
+    for componentstr in [hourstr, minutestr, secondstr]:
+        if componentstr is not None:
+            if "." in componentstr:
+                intstr, fractionalstr = componentstr.split(".", 1)
+
+                if intstr.isdigit() is False:
+                    raise ISOFormatError(
+                        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
+                    )
+            else:
+                if componentstr.isdigit() is False:
+                    raise ISOFormatError(
+                        '"{0}" is not a valid ISO 8601 duration.'.format(isodurationstr)
+                    )
+
+    # Parse any date components
+    durationdict = {"PnY": None, "PnM": None, "PnW": None, "PnD": None}
+
+    if len(datestr) > 1:
+        durationdict = _parse_duration_prescribed_notime(datestr)
+
+    durationdict.update({"TnH": hourstr, "TnM": minutestr, "TnS": secondstr})
+
+    return durationdict
+
+
+def _parse_duration_combined(durationstr):
+    # Period of the form P<date>T<time>
+
+    # Split the string in to its component parts
+    datepart, timepart = durationstr[1:].split("T", 1)  # We skip the 'P'
+
+    datevalue = parse_date(datepart, builder=TupleBuilder)
+    timevalue = parse_time(timepart, builder=TupleBuilder)
+
+    return {
+        "PnY": datevalue.YYYY,
+        "PnM": datevalue.MM,
+        "PnD": datevalue.DD,
+        "TnH": timevalue.hh,
+        "TnM": timevalue.mm,
+        "TnS": timevalue.ss,
+    }
+
+
+def _has_any_component(durationstr, components):
+    # Given a duration string, and a list of components, returns True
+    # if any of the listed components are present, False otherwise.
+    #
+    # For instance:
+    # durationstr = 'P1Y'
+    # components = ['Y', 'M']
+    #
+    # returns True
+    #
+    # durationstr = 'P1Y'
+    # components = ['M', 'D']
+    #
+    # returns False
+
+    for component in components:
+        if durationstr.find(component) != -1:
+            return True
+
+    return False
diff --git a/libs/aniso8601/exceptions.py b/libs/aniso8601/exceptions.py
new file mode 100644
index 000000000..c14b44421
--- /dev/null
+++ b/libs/aniso8601/exceptions.py
@@ -0,0 +1,51 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+
+class ISOFormatError(ValueError):
+    """Raised when ISO 8601 string fails a format check."""
+
+
+class RangeCheckError(ValueError):
+    """Parent type of range check errors."""
+
+
+class YearOutOfBoundsError(RangeCheckError):
+    """Raised when year exceeds limits."""
+
+
+class MonthOutOfBoundsError(RangeCheckError):
+    """Raised when month is outside of 1..12."""
+
+
+class WeekOutOfBoundsError(RangeCheckError):
+    """Raised when week exceeds a year."""
+
+
+class DayOutOfBoundsError(RangeCheckError):
+    """Raised when day is outside of 1..365, 1..366 for leap year."""
+
+
+class HoursOutOfBoundsError(RangeCheckError):
+    """Raise when parsed hours are greater than 24."""
+
+
+class MinutesOutOfBoundsError(RangeCheckError):
+    """Raise when parsed seconds are greater than 60."""
+
+
+class SecondsOutOfBoundsError(RangeCheckError):
+    """Raise when parsed seconds are greater than 60."""
+
+
+class MidnightBoundsError(RangeCheckError):
+    """Raise when parsed time has an hour of 24 but is not midnight."""
+
+
+class LeapSecondError(RangeCheckError):
+    """Raised when attempting to parse a leap second"""
diff --git a/libs/aniso8601/interval.py b/libs/aniso8601/interval.py
new file mode 100644
index 000000000..cd0184c6b
--- /dev/null
+++ b/libs/aniso8601/interval.py
@@ -0,0 +1,350 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+from aniso8601.builders import DatetimeTuple, DateTuple, TupleBuilder
+from aniso8601.builders.python import PythonTimeBuilder
+from aniso8601.compat import is_string
+from aniso8601.date import parse_date
+from aniso8601.duration import parse_duration
+from aniso8601.exceptions import ISOFormatError
+from aniso8601.resolution import IntervalResolution
+from aniso8601.time import parse_datetime, parse_time
+
+
+def get_interval_resolution(
+    isointervalstr, intervaldelimiter="/", datetimedelimiter="T"
+):
+    isointervaltuple = parse_interval(
+        isointervalstr,
+        intervaldelimiter=intervaldelimiter,
+        datetimedelimiter=datetimedelimiter,
+        builder=TupleBuilder,
+    )
+
+    return _get_interval_resolution(isointervaltuple)
+
+
+def get_repeating_interval_resolution(
+    isointervalstr, intervaldelimiter="/", datetimedelimiter="T"
+):
+    repeatingintervaltuple = parse_repeating_interval(
+        isointervalstr,
+        intervaldelimiter=intervaldelimiter,
+        datetimedelimiter=datetimedelimiter,
+        builder=TupleBuilder,
+    )
+
+    return _get_interval_resolution(repeatingintervaltuple.interval)
+
+
+def _get_interval_resolution(intervaltuple):
+    if intervaltuple.start is not None and intervaltuple.end is not None:
+        return max(
+            _get_interval_component_resolution(intervaltuple.start),
+            _get_interval_component_resolution(intervaltuple.end),
+        )
+
+    if intervaltuple.start is not None and intervaltuple.duration is not None:
+        return max(
+            _get_interval_component_resolution(intervaltuple.start),
+            _get_interval_component_resolution(intervaltuple.duration),
+        )
+
+    return max(
+        _get_interval_component_resolution(intervaltuple.end),
+        _get_interval_component_resolution(intervaltuple.duration),
+    )
+
+
+def _get_interval_component_resolution(componenttuple):
+    if type(componenttuple) is DateTuple:
+        if componenttuple.DDD is not None:
+            # YYYY-DDD
+            # YYYYDDD
+            return IntervalResolution.Ordinal
+
+        if componenttuple.D is not None:
+            # YYYY-Www-D
+            # YYYYWwwD
+            return IntervalResolution.Weekday
+
+        if componenttuple.Www is not None:
+            # YYYY-Www
+            # YYYYWww
+            return IntervalResolution.Week
+
+        if componenttuple.DD is not None:
+            # YYYY-MM-DD
+            # YYYYMMDD
+            return IntervalResolution.Day
+
+        if componenttuple.MM is not None:
+            # YYYY-MM
+            return IntervalResolution.Month
+
+        # Y[YYY]
+        return IntervalResolution.Year
+    elif type(componenttuple) is DatetimeTuple:
+        # Datetime
+        if componenttuple.time.ss is not None:
+            return IntervalResolution.Seconds
+
+        if componenttuple.time.mm is not None:
+            return IntervalResolution.Minutes
+
+        return IntervalResolution.Hours
+
+    # Duration
+    if componenttuple.TnS is not None:
+        return IntervalResolution.Seconds
+
+    if componenttuple.TnM is not None:
+        return IntervalResolution.Minutes
+
+    if componenttuple.TnH is not None:
+        return IntervalResolution.Hours
+
+    if componenttuple.PnD is not None:
+        return IntervalResolution.Day
+
+    if componenttuple.PnW is not None:
+        return IntervalResolution.Week
+
+    if componenttuple.PnM is not None:
+        return IntervalResolution.Month
+
+    return IntervalResolution.Year
+
+
+def parse_interval(
+    isointervalstr,
+    intervaldelimiter="/",
+    datetimedelimiter="T",
+    builder=PythonTimeBuilder,
+):
+    # Given a string representing an ISO 8601 interval, return an
+    # interval built by the given builder. Valid formats are:
+    #
+    # <start>/<end>
+    # <start>/<duration>
+    # <duration>/<end>
+    #
+    # The <start> and <end> values can represent dates, or datetimes,
+    # not times.
+    #
+    # The format:
+    #
+    # <duration>
+    #
+    # Is expressly not supported as there is no way to provide the additional
+    # required context.
+
+    if is_string(isointervalstr) is False:
+        raise ValueError("Interval must be string.")
+
+    if len(isointervalstr) == 0:
+        raise ISOFormatError("Interval string is empty.")
+
+    if isointervalstr[0] == "R":
+        raise ISOFormatError(
+            "ISO 8601 repeating intervals must be parsed "
+            "with parse_repeating_interval."
+        )
+
+    intervaldelimitercount = isointervalstr.count(intervaldelimiter)
+
+    if intervaldelimitercount == 0:
+        raise ISOFormatError(
+            'Interval delimiter "{0}" is not in interval '
+            'string "{1}".'.format(intervaldelimiter, isointervalstr)
+        )
+
+    if intervaldelimitercount > 1:
+        raise ISOFormatError(
+            "{0} is not a valid ISO 8601 interval".format(isointervalstr)
+        )
+
+    return _parse_interval(
+        isointervalstr, builder, intervaldelimiter, datetimedelimiter
+    )
+
+
+def parse_repeating_interval(
+    isointervalstr,
+    intervaldelimiter="/",
+    datetimedelimiter="T",
+    builder=PythonTimeBuilder,
+):
+    # Given a string representing an ISO 8601 interval repeating, return an
+    # interval built by the given builder. Valid formats are:
+    #
+    # Rnn/<interval>
+    # R/<interval>
+
+    if not isinstance(isointervalstr, str):
+        raise ValueError("Interval must be string.")
+
+    if len(isointervalstr) == 0:
+        raise ISOFormatError("Repeating interval string is empty.")
+
+    if isointervalstr[0] != "R":
+        raise ISOFormatError("ISO 8601 repeating interval must start " "with an R.")
+
+    if intervaldelimiter not in isointervalstr:
+        raise ISOFormatError(
+            'Interval delimiter "{0}" is not in interval '
+            'string "{1}".'.format(intervaldelimiter, isointervalstr)
+        )
+
+    # Parse the number of iterations
+    iterationpart, intervalpart = isointervalstr.split(intervaldelimiter, 1)
+
+    if len(iterationpart) > 1:
+        R = False
+        Rnn = iterationpart[1:]
+    else:
+        R = True
+        Rnn = None
+
+    interval = _parse_interval(
+        intervalpart, TupleBuilder, intervaldelimiter, datetimedelimiter
+    )
+
+    return builder.build_repeating_interval(R=R, Rnn=Rnn, interval=interval)
+
+
+def _parse_interval(
+    isointervalstr, builder, intervaldelimiter="/", datetimedelimiter="T"
+):
+    # Returns a tuple containing the start of the interval, the end of the
+    # interval, and or the interval duration
+
+    firstpart, secondpart = isointervalstr.split(intervaldelimiter)
+
+    if len(firstpart) == 0 or len(secondpart) == 0:
+        raise ISOFormatError(
+            "{0} is not a valid ISO 8601 interval".format(isointervalstr)
+        )
+
+    if firstpart[0] == "P":
+        # <duration>/<end>
+        # Notice that these are not returned 'in order' (earlier to later), this
+        # is to maintain consistency with parsing <start>/<end> durations, as
+        # well as making repeating interval code cleaner. Users who desire
+        # durations to be in order can use the 'sorted' operator.
+        duration = parse_duration(firstpart, builder=TupleBuilder)
+
+        # We need to figure out if <end> is a date, or a datetime
+        if secondpart.find(datetimedelimiter) != -1:
+            # <end> is a datetime
+            endtuple = parse_datetime(
+                secondpart, delimiter=datetimedelimiter, builder=TupleBuilder
+            )
+        else:
+            endtuple = parse_date(secondpart, builder=TupleBuilder)
+
+        return builder.build_interval(end=endtuple, duration=duration)
+    elif secondpart[0] == "P":
+        # <start>/<duration>
+        # We need to figure out if <start> is a date, or a datetime
+        duration = parse_duration(secondpart, builder=TupleBuilder)
+
+        if firstpart.find(datetimedelimiter) != -1:
+            # <start> is a datetime
+            starttuple = parse_datetime(
+                firstpart, delimiter=datetimedelimiter, builder=TupleBuilder
+            )
+        else:
+            # <start> must just be a date
+            starttuple = parse_date(firstpart, builder=TupleBuilder)
+
+        return builder.build_interval(start=starttuple, duration=duration)
+
+    # <start>/<end>
+    if firstpart.find(datetimedelimiter) != -1:
+        # Both parts are datetimes
+        starttuple = parse_datetime(
+            firstpart, delimiter=datetimedelimiter, builder=TupleBuilder
+        )
+    else:
+        starttuple = parse_date(firstpart, builder=TupleBuilder)
+
+    endtuple = _parse_interval_end(secondpart, starttuple, datetimedelimiter)
+
+    return builder.build_interval(start=starttuple, end=endtuple)
+
+
+def _parse_interval_end(endstr, starttuple, datetimedelimiter):
+    datestr = None
+    timestr = None
+
+    monthstr = None
+    daystr = None
+
+    concise = False
+
+    if type(starttuple) is DateTuple:
+        startdatetuple = starttuple
+    else:
+        # Start is a datetime
+        startdatetuple = starttuple.date
+
+    if datetimedelimiter in endstr:
+        datestr, timestr = endstr.split(datetimedelimiter, 1)
+    elif ":" in endstr:
+        timestr = endstr
+    else:
+        datestr = endstr
+
+    if timestr is not None:
+        endtimetuple = parse_time(timestr, builder=TupleBuilder)
+
+    # End is just a time
+    if datestr is None:
+        return endtimetuple
+
+    # Handle backwards concise representation
+    if datestr.count("-") == 1:
+        monthstr, daystr = datestr.split("-")
+        concise = True
+    elif len(datestr) <= 2:
+        daystr = datestr
+        concise = True
+    elif len(datestr) <= 4:
+        monthstr = datestr[0:2]
+        daystr = datestr[2:]
+        concise = True
+
+    if concise is True:
+        concisedatestr = startdatetuple.YYYY
+
+        # Separators required because concise elements may be missing digits
+        if monthstr is not None:
+            concisedatestr += "-" + monthstr
+        elif startdatetuple.MM is not None:
+            concisedatestr += "-" + startdatetuple.MM
+
+        concisedatestr += "-" + daystr
+
+        enddatetuple = parse_date(concisedatestr, builder=TupleBuilder)
+
+        # Clear unsupplied components
+        if monthstr is None:
+            enddatetuple = TupleBuilder.build_date(DD=enddatetuple.DD)
+        else:
+            # Year not provided
+            enddatetuple = TupleBuilder.build_date(
+                MM=enddatetuple.MM, DD=enddatetuple.DD
+            )
+    else:
+        enddatetuple = parse_date(datestr, builder=TupleBuilder)
+
+    if timestr is None:
+        return enddatetuple
+
+    return TupleBuilder.build_datetime(enddatetuple, endtimetuple)
diff --git a/libs/aniso8601/resolution.py b/libs/aniso8601/resolution.py
new file mode 100644
index 000000000..eca2d4e7e
--- /dev/null
+++ b/libs/aniso8601/resolution.py
@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+from aniso8601 import compat
+
+
+class DateResolution(object):
+    Year, Month, Week, Weekday, Day, Ordinal = list(compat.range(6))
+
+
+class DurationResolution(object):
+    Years, Months, Weeks, Days, Hours, Minutes, Seconds = list(compat.range(7))
+
+
+class IntervalResolution(object):
+    Year, Month, Week, Weekday, Day, Ordinal, Hours, Minutes, Seconds = list(
+        compat.range(9)
+    )
+
+
+class TimeResolution(object):
+    Seconds, Minutes, Hours = list(compat.range(3))
diff --git a/libs/aniso8601/tests/__init__.py b/libs/aniso8601/tests/__init__.py
new file mode 100644
index 000000000..1a94e017a
--- /dev/null
+++ b/libs/aniso8601/tests/__init__.py
@@ -0,0 +1,7 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
diff --git a/libs/aniso8601/tests/compat.py b/libs/aniso8601/tests/compat.py
new file mode 100644
index 000000000..6c5266589
--- /dev/null
+++ b/libs/aniso8601/tests/compat.py
@@ -0,0 +1,16 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import sys
+
+PY2 = sys.version_info[0] == 2
+
+if PY2:
+    import mock  # pylint: disable=import-error
+else:
+    from unittest import mock
diff --git a/libs/aniso8601/tests/test_compat.py b/libs/aniso8601/tests/test_compat.py
new file mode 100644
index 000000000..2f7988331
--- /dev/null
+++ b/libs/aniso8601/tests/test_compat.py
@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+from aniso8601.compat import PY2, is_string
+
+
+class TestCompatFunctions(unittest.TestCase):
+    def test_is_string(self):
+        self.assertTrue(is_string("asdf"))
+        self.assertTrue(is_string(""))
+
+        # pylint: disable=undefined-variable
+        if PY2 is True:
+            self.assertTrue(is_string(unicode("asdf")))
+
+        self.assertFalse(is_string(None))
+        self.assertFalse(is_string(123))
+        self.assertFalse(is_string(4.56))
+        self.assertFalse(is_string([]))
+        self.assertFalse(is_string({}))
diff --git a/libs/aniso8601/tests/test_date.py b/libs/aniso8601/tests/test_date.py
new file mode 100644
index 000000000..54e3076eb
--- /dev/null
+++ b/libs/aniso8601/tests/test_date.py
@@ -0,0 +1,303 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+import aniso8601
+from aniso8601.date import get_date_resolution, parse_date
+from aniso8601.exceptions import DayOutOfBoundsError, ISOFormatError
+from aniso8601.resolution import DateResolution
+from aniso8601.tests.compat import mock
+
+
+class TestDateResolutionFunctions(unittest.TestCase):
+    def test_get_date_resolution_year(self):
+        self.assertEqual(get_date_resolution("2013"), DateResolution.Year)
+        self.assertEqual(get_date_resolution("0001"), DateResolution.Year)
+        self.assertEqual(get_date_resolution("19"), DateResolution.Year)
+
+    def test_get_date_resolution_month(self):
+        self.assertEqual(get_date_resolution("1981-04"), DateResolution.Month)
+
+    def test_get_date_resolution_week(self):
+        self.assertEqual(get_date_resolution("2004-W53"), DateResolution.Week)
+        self.assertEqual(get_date_resolution("2009-W01"), DateResolution.Week)
+        self.assertEqual(get_date_resolution("2004W53"), DateResolution.Week)
+
+    def test_get_date_resolution_day(self):
+        self.assertEqual(get_date_resolution("2004-04-11"), DateResolution.Day)
+        self.assertEqual(get_date_resolution("20090121"), DateResolution.Day)
+
+    def test_get_date_resolution_year_weekday(self):
+        self.assertEqual(get_date_resolution("2004-W53-6"), DateResolution.Weekday)
+        self.assertEqual(get_date_resolution("2004W536"), DateResolution.Weekday)
+
+    def test_get_date_resolution_year_ordinal(self):
+        self.assertEqual(get_date_resolution("1981-095"), DateResolution.Ordinal)
+        self.assertEqual(get_date_resolution("1981095"), DateResolution.Ordinal)
+
+    def test_get_date_resolution_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                get_date_resolution(testtuple)
+
+    def test_get_date_resolution_extended_year(self):
+        testtuples = ("+2000", "+30000")
+
+        for testtuple in testtuples:
+            with self.assertRaises(NotImplementedError):
+                get_date_resolution(testtuple)
+
+    def test_get_date_resolution_badweek(self):
+        testtuples = ("2004-W1", "2004W1")
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                get_date_resolution(testtuple)
+
+    def test_get_date_resolution_badweekday(self):
+        testtuples = ("2004-W53-67", "2004W5367")
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                get_date_resolution(testtuple)
+
+    def test_get_date_resolution_badstr(self):
+        testtuples = (
+            "W53",
+            "2004-W",
+            "2014-01-230",
+            "2014-012-23",
+            "201-01-23",
+            "201401230",
+            "201401",
+            "",
+        )
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                get_date_resolution(testtuple)
+
+
+class TestDateParserFunctions(unittest.TestCase):
+    def test_parse_date(self):
+        testtuples = (
+            (
+                "2013",
+                {
+                    "YYYY": "2013",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "0001",
+                {
+                    "YYYY": "0001",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "19",
+                {
+                    "YYYY": "19",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "1981-04-05",
+                {
+                    "YYYY": "1981",
+                    "MM": "04",
+                    "DD": "05",
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "19810405",
+                {
+                    "YYYY": "1981",
+                    "MM": "04",
+                    "DD": "05",
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "1981-04",
+                {
+                    "YYYY": "1981",
+                    "MM": "04",
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "2004-W53",
+                {
+                    "YYYY": "2004",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "53",
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "2009-W01",
+                {
+                    "YYYY": "2009",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "01",
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "2004-W53-6",
+                {
+                    "YYYY": "2004",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "53",
+                    "D": "6",
+                    "DDD": None,
+                },
+            ),
+            (
+                "2004W53",
+                {
+                    "YYYY": "2004",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "53",
+                    "D": None,
+                    "DDD": None,
+                },
+            ),
+            (
+                "2004W536",
+                {
+                    "YYYY": "2004",
+                    "MM": None,
+                    "DD": None,
+                    "Www": "53",
+                    "D": "6",
+                    "DDD": None,
+                },
+            ),
+            (
+                "1981-095",
+                {
+                    "YYYY": "1981",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": "095",
+                },
+            ),
+            (
+                "1981095",
+                {
+                    "YYYY": "1981",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": "095",
+                },
+            ),
+            (
+                "1980366",
+                {
+                    "YYYY": "1980",
+                    "MM": None,
+                    "DD": None,
+                    "Www": None,
+                    "D": None,
+                    "DDD": "366",
+                },
+            ),
+        )
+
+        for testtuple in testtuples:
+            with mock.patch.object(
+                aniso8601.date.PythonTimeBuilder, "build_date"
+            ) as mockBuildDate:
+                mockBuildDate.return_value = testtuple[1]
+
+                result = parse_date(testtuple[0])
+
+                self.assertEqual(result, testtuple[1])
+                mockBuildDate.assert_called_once_with(**testtuple[1])
+
+    def test_parse_date_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                parse_date(testtuple, builder=None)
+
+    def test_parse_date_badstr(self):
+        testtuples = (
+            "W53",
+            "2004-W",
+            "2014-01-230",
+            "2014-012-23",
+            "201-01-23",
+            "201401230",
+            "201401",
+            "9999 W53",
+            "20.50230",
+            "198104",
+            "bad",
+            "",
+        )
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_date(testtuple, builder=None)
+
+    def test_parse_date_mockbuilder(self):
+        mockBuilder = mock.Mock()
+
+        expectedargs = {
+            "YYYY": "1981",
+            "MM": "04",
+            "DD": "05",
+            "Www": None,
+            "D": None,
+            "DDD": None,
+        }
+
+        mockBuilder.build_date.return_value = expectedargs
+
+        result = parse_date("1981-04-05", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_date.assert_called_once_with(**expectedargs)
diff --git a/libs/aniso8601/tests/test_decimalfraction.py b/libs/aniso8601/tests/test_decimalfraction.py
new file mode 100644
index 000000000..dc52f2406
--- /dev/null
+++ b/libs/aniso8601/tests/test_decimalfraction.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+from aniso8601.decimalfraction import normalize
+
+
+class TestDecimalFractionFunctions(unittest.TestCase):
+    def test_normalize(self):
+        self.assertEqual(normalize(""), "")
+        self.assertEqual(normalize("12.34"), "12.34")
+        self.assertEqual(normalize("123,45"), "123.45")
+        self.assertEqual(normalize("123,45,67"), "123.45.67")
diff --git a/libs/aniso8601/tests/test_duration.py b/libs/aniso8601/tests/test_duration.py
new file mode 100644
index 000000000..0d7d40a4d
--- /dev/null
+++ b/libs/aniso8601/tests/test_duration.py
@@ -0,0 +1,1402 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+import aniso8601
+from aniso8601.duration import (
+    _has_any_component,
+    _parse_duration_combined,
+    _parse_duration_prescribed,
+    _parse_duration_prescribed_notime,
+    _parse_duration_prescribed_time,
+    get_duration_resolution,
+    parse_duration,
+)
+from aniso8601.exceptions import ISOFormatError
+from aniso8601.resolution import DurationResolution
+from aniso8601.tests.compat import mock
+
+
+class TestDurationParserFunctions(unittest.TestCase):
+    def test_get_duration_resolution_years(self):
+        self.assertEqual(get_duration_resolution("P1Y"), DurationResolution.Years)
+        self.assertEqual(get_duration_resolution("P1,5Y"), DurationResolution.Years)
+        self.assertEqual(get_duration_resolution("P1.5Y"), DurationResolution.Years)
+
+    def test_get_duration_resolution_months(self):
+        self.assertEqual(get_duration_resolution("P1Y2M"), DurationResolution.Months)
+        self.assertEqual(get_duration_resolution("P1M"), DurationResolution.Months)
+        self.assertEqual(get_duration_resolution("P1,5M"), DurationResolution.Months)
+        self.assertEqual(get_duration_resolution("P1.5M"), DurationResolution.Months)
+
+    def test_get_duration_resolution_weeks(self):
+        self.assertEqual(get_duration_resolution("P1W"), DurationResolution.Weeks)
+        self.assertEqual(get_duration_resolution("P1,5W"), DurationResolution.Weeks)
+        self.assertEqual(get_duration_resolution("P1.5W"), DurationResolution.Weeks)
+
+    def test_get_duration_resolution_days(self):
+        self.assertEqual(get_duration_resolution("P1Y2M3D"), DurationResolution.Days)
+        self.assertEqual(get_duration_resolution("P1Y2M3,5D"), DurationResolution.Days)
+        self.assertEqual(get_duration_resolution("P1Y2M3.5D"), DurationResolution.Days)
+        self.assertEqual(get_duration_resolution("P1D"), DurationResolution.Days)
+        self.assertEqual(get_duration_resolution("P1,5D"), DurationResolution.Days)
+        self.assertEqual(get_duration_resolution("P1.5D"), DurationResolution.Days)
+
+    def test_get_duration_resolution_hours(self):
+        self.assertEqual(
+            get_duration_resolution("P1Y2M3DT4H"), DurationResolution.Hours
+        )
+        self.assertEqual(get_duration_resolution("PT4H"), DurationResolution.Hours)
+
+    def test_get_duration_resolution_minutes(self):
+        self.assertEqual(
+            get_duration_resolution("P1Y2M3DT4H5M"), DurationResolution.Minutes
+        )
+        self.assertEqual(get_duration_resolution("PT4H5M"), DurationResolution.Minutes)
+
+    def test_get_duration_resolution_seconds(self):
+        self.assertEqual(
+            get_duration_resolution("P1Y2M3DT4H54M6S"), DurationResolution.Seconds
+        )
+        self.assertEqual(
+            get_duration_resolution("P1Y2M3DT4H54M6,5S"), DurationResolution.Seconds
+        )
+        self.assertEqual(
+            get_duration_resolution("P1Y2M3DT4H54M6.5S"), DurationResolution.Seconds
+        )
+        self.assertEqual(
+            get_duration_resolution("PT4H54M6,5S"), DurationResolution.Seconds
+        )
+        self.assertEqual(
+            get_duration_resolution("PT4H54M6.5S"), DurationResolution.Seconds
+        )
+        self.assertEqual(
+            get_duration_resolution("PT0.0000001S"), DurationResolution.Seconds
+        )
+        self.assertEqual(
+            get_duration_resolution("PT2.0000048S"), DurationResolution.Seconds
+        )
+        self.assertEqual(
+            get_duration_resolution("P0003-06-04T12:30:05"), DurationResolution.Seconds
+        )
+        self.assertEqual(
+            get_duration_resolution("P0003-06-04T12:30:05.5"),
+            DurationResolution.Seconds,
+        )
+        self.assertEqual(
+            get_duration_resolution("P0001-02-03T14:43:59.9999997"),
+            DurationResolution.Seconds,
+        )
+
+    def test_parse_duration(self):
+        testtuples = (
+            (
+                "P1Y2M3DT4H54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y2M3DT4H54M6,5S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "P1Y2M3DT4H54M6.5S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "P1YT4H",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1YT54M",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1YT6S",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1YT4H54M",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1YT4H6S",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1YT54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1YT4H54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P2MT4H",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": None,
+                },
+            ),
+            (
+                "P2MT54M",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P2MT6S",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P2MT4H54M",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P2MT4H6S",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P2MT54M6S",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P2MT4H54M6S",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P3DT4H",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": None,
+                },
+            ),
+            (
+                "P3DT54M",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P3DT6S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P3DT4H54M",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P3DT4H6S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P3DT54M6S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P3DT4H54M6S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y2MT4H",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1Y2MT54M",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1Y2MT6S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y2MT4H54M",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1Y2MT4H6S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y2MT54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y2MT4H54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y3DT4H",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1Y3DT54M",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1Y3DT6S",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y3DT4H54M",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P1Y3DT4H6S",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y3DT54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y3DT4H54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P2M3DT4H",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": None,
+                },
+            ),
+            (
+                "P2M3DT54M",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P2M3DT6S",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P2M3DT4H54M",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": None,
+                },
+            ),
+            (
+                "P2M3DT4H6S",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P2M3DT54M6S",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": None,
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P2M3DT4H54M6S",
+                {
+                    "PnY": None,
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "PT4H54M6,5S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "PT4H54M6.5S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "PT4H",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": None,
+                },
+            ),
+            (
+                "PT5M",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "5",
+                    "TnS": None,
+                },
+            ),
+            (
+                "PT6S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "PT1H2M",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "1",
+                    "TnM": "2",
+                    "TnS": None,
+                },
+            ),
+            (
+                "PT3H4S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "3",
+                    "TnM": None,
+                    "TnS": "4",
+                },
+            ),
+            (
+                "PT5M6S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "5",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "PT0.0000001S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "0.0000001",
+                },
+            ),
+            (
+                "PT2.0000048S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "2.0000048",
+                },
+            ),
+            ("P1Y", {"PnY": "1", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1,5Y", {"PnY": "1.5", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1.5Y", {"PnY": "1.5", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1M", {"PnY": None, "PnM": "1", "PnW": None, "PnD": None}),
+            ("P1,5M", {"PnY": None, "PnM": "1.5", "PnW": None, "PnD": None}),
+            ("P1.5M", {"PnY": None, "PnM": "1.5", "PnW": None, "PnD": None}),
+            ("P1W", {"PnY": None, "PnM": None, "PnW": "1", "PnD": None}),
+            ("P1,5W", {"PnY": None, "PnM": None, "PnW": "1.5", "PnD": None}),
+            ("P1.5W", {"PnY": None, "PnM": None, "PnW": "1.5", "PnD": None}),
+            ("P1D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1"}),
+            ("P1,5D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1.5"}),
+            ("P1.5D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1.5"}),
+            ("P1Y2M3D", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": "3"}),
+            ("P1Y2M3,5D", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": "3.5"}),
+            ("P1Y2M3.5D", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": "3.5"}),
+            ("P1Y2M", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": None}),
+            (
+                "P0003-06-04T12:30:05",
+                {
+                    "PnY": "0003",
+                    "PnM": "06",
+                    "PnD": "04",
+                    "TnH": "12",
+                    "TnM": "30",
+                    "TnS": "05",
+                },
+            ),
+            (
+                "P0003-06-04T12:30:05.5",
+                {
+                    "PnY": "0003",
+                    "PnM": "06",
+                    "PnD": "04",
+                    "TnH": "12",
+                    "TnM": "30",
+                    "TnS": "05.5",
+                },
+            ),
+            (
+                "P0001-02-03T14:43:59.9999997",
+                {
+                    "PnY": "0001",
+                    "PnM": "02",
+                    "PnD": "03",
+                    "TnH": "14",
+                    "TnM": "43",
+                    "TnS": "59.9999997",
+                },
+            ),
+        )
+
+        for testtuple in testtuples:
+            with mock.patch.object(
+                aniso8601.duration.PythonTimeBuilder, "build_duration"
+            ) as mockBuildDuration:
+                mockBuildDuration.return_value = testtuple[1]
+
+                result = parse_duration(testtuple[0])
+
+                self.assertEqual(result, testtuple[1])
+                mockBuildDuration.assert_called_once_with(**testtuple[1])
+
+    def test_parse_duration_mockbuilder(self):
+        mockBuilder = mock.Mock()
+
+        expectedargs = {
+            "PnY": "1",
+            "PnM": "2",
+            "PnW": None,
+            "PnD": "3",
+            "TnH": "4",
+            "TnM": "54",
+            "TnS": "6",
+        }
+
+        mockBuilder.build_duration.return_value = expectedargs
+
+        result = parse_duration("P1Y2M3DT4H54M6S", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_duration.assert_called_once_with(**expectedargs)
+
+    def test_parse_duration_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                parse_duration(testtuple, builder=None)
+
+    def test_parse_duration_nop(self):
+        with self.assertRaises(ISOFormatError):
+            # Duration must start with a P
+            parse_duration("1Y2M3DT4H54M6S", builder=None)
+
+    def test_parse_duration_weekcombination(self):
+        # Week designator cannot be combined with other time designators
+        # https://bitbucket.org/nielsenb/aniso8601/issues/2/week-designators-should-not-be-combinable
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1Y2W", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1M2W", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P2W3D", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1Y2W3D", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1M2W3D", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1Y1M2W3D", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P7WT4H", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P7WT54M", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P7WT6S", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P7WT4H54M", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P7WT4H6S", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P7WT54M6S", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P7WT4H54M6S", builder=None)
+
+    def test_parse_duration_negative(self):
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P-1Y", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P-2M", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P-3D", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P-T4H", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P-T54M", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P-T6S", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P-7W", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P-1Y2M3DT4H54M6S", builder=None)
+
+    def test_parse_duration_outoforder(self):
+        # Ensure durations are required to be in the correct order
+        # https://bitbucket.org/nielsenb/aniso8601/issues/7/durations-with-time-components-before-t
+        # https://bitbucket.org/nielsenb/aniso8601/issues/8/durations-with-components-in-wrong-order
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1S", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1D1S", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1H1M", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("1Y2M3D1SPT1M", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1Y2M3D2MT1S", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P2M3D1ST1Y1M", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1Y2M2MT3D1S", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("P1D1Y1M", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_duration("PT1S1H", builder=None)
+
+    def test_parse_duration_badstr(self):
+        testtuples = (
+            "PPPPPPPPPPPPPPPPPPPPPPPPPPPP",
+            "PTT",
+            "PX7DDDTX8888UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU"
+            "UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU8888888888888888H$H",
+            "P1Y2M3X.4D",
+            "P1Y2M3.4XD",
+            "P1Y2M3DT4H5M6XS",
+            "PT4H5M6X.2S",
+            "bad",
+            "",
+        )
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_duration(testtuple, builder=None)
+
+    def test_parse_duration_prescribed(self):
+        testtuples = (
+            (
+                "P1Y2M3DT4H54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y2M3DT4H54M6,5S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "P1Y2M3DT4H54M6.5S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "PT4H54M6,5S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "PT4H54M6.5S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            ("P1Y2M3D", {"PnY": "1", "PnM": "2", "" "PnW": None, "PnD": "3"}),
+            ("P1Y2M3,5D", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": "3.5"}),
+            ("P1Y2M3.5D", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": "3.5"}),
+            ("P1Y2M", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": None}),
+            ("P1Y", {"PnY": "1", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1,5Y", {"PnY": "1.5", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1.5Y", {"PnY": "1.5", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1M", {"PnY": None, "PnM": "1", "PnW": None, "PnD": None}),
+            ("P1,5M", {"PnY": None, "PnM": "1.5", "PnW": None, "PnD": None}),
+            ("P1.5M", {"PnY": None, "PnM": "1.5", "PnW": None, "PnD": None}),
+            ("P1W", {"PnY": None, "PnM": None, "PnW": "1", "PnD": None}),
+            ("P1,5W", {"PnY": None, "PnM": None, "PnW": "1.5", "PnD": None}),
+            ("P1.5W", {"PnY": None, "PnM": None, "PnW": "1.5", "PnD": None}),
+            ("P1D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1"}),
+            ("P1,5D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1.5"}),
+            ("P1.5D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1.5"}),
+        )
+
+        for testtuple in testtuples:
+            result = _parse_duration_prescribed(testtuple[0])
+
+            self.assertEqual(result, testtuple[1])
+
+    def test_parse_duration_prescribed_negative(self):
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-1Y")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-2M")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-3D")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-4W")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-1Y2M3D")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-T1H")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-T2M")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-T3S")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P-1Y2M3DT4H54M6S")
+
+    def test_parse_duration_prescribed_multiplefractions(self):
+        with self.assertRaises(ISOFormatError):
+            # Multiple fractions are not allowed
+            _parse_duration_prescribed("P1Y2M3DT4H5.1234M6.1234S")
+
+    def test_parse_duration_prescribed_middlefraction(self):
+        with self.assertRaises(ISOFormatError):
+            # Fraction only allowed on final component
+            _parse_duration_prescribed("P1Y2M3DT4H5.1234M6S")
+
+    def test_parse_duration_prescribed_suffixgarbage(self):
+        # Don't allow garbage after the duration
+        # https://bitbucket.org/nielsenb/aniso8601/issues/9/durations-with-trailing-garbage-are-parsed
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed("P1Dasdfasdf")
+
+    def test_parse_duration_prescribed_notime(self):
+        testtuples = (
+            ("P1Y2M3D", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": "3"}),
+            ("P1Y2M3,5D", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": "3.5"}),
+            ("P1Y2M3.5D", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": "3.5"}),
+            ("P1Y3D", {"PnY": "1", "PnM": None, "PnW": None, "PnD": "3"}),
+            ("P1Y2M", {"PnY": "1", "PnM": "2", "PnW": None, "PnD": None}),
+            ("P2M3D", {"PnY": None, "PnM": "2", "PnW": None, "PnD": "3"}),
+            ("P1Y", {"PnY": "1", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1,5Y", {"PnY": "1.5", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1.5Y", {"PnY": "1.5", "PnM": None, "PnW": None, "PnD": None}),
+            ("P1M", {"PnY": None, "PnM": "1", "PnW": None, "PnD": None}),
+            ("P1,5M", {"PnY": None, "PnM": "1.5", "PnW": None, "PnD": None}),
+            ("P1.5M", {"PnY": None, "PnM": "1.5", "PnW": None, "PnD": None}),
+            ("P1W", {"PnY": None, "PnM": None, "PnW": "1", "PnD": None}),
+            ("P1,5W", {"PnY": None, "PnM": None, "PnW": "1.5", "PnD": None}),
+            ("P1.5W", {"PnY": None, "PnM": None, "PnW": "1.5", "PnD": None}),
+            ("P1D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1"}),
+            ("P1,5D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1.5"}),
+            ("P1.5D", {"PnY": None, "PnM": None, "PnW": None, "PnD": "1.5"}),
+        )
+
+        for testtuple in testtuples:
+            result = _parse_duration_prescribed_notime(testtuple[0])
+
+            self.assertEqual(result, testtuple[1])
+
+    def test_parse_duration_prescribed_notime_timepart(self):
+        # Ensure no time part is allowed
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1S")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1D1S")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1H1M")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1Y2M3D4H")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1Y2M3D4H5S")
+
+    def test_parse_duration_prescribed_notime_outoforder(self):
+        # Ensure durations are required to be in the correct order
+        # https://bitbucket.org/nielsenb/aniso8601/issues/8/durations-with-components-in-wrong-order
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1H1M")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1D1Y1M")
+
+    def test_parse_duration_prescribed_notime_badstr(self):
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1S")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_notime("P1D1S")
+
+    def test_parse_duration_prescribed_time(self):
+        testtuples = (
+            (
+                "P1Y2M3DT4H54M6S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6",
+                },
+            ),
+            (
+                "P1Y2M3DT4H54M6,5S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "P1Y2M3DT4H54M6.5S",
+                {
+                    "PnY": "1",
+                    "PnM": "2",
+                    "PnW": None,
+                    "PnD": "3",
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "PT4H54M6,5S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "PT4H54M6.5S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": "54",
+                    "TnS": "6.5",
+                },
+            ),
+            (
+                "PT4H",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "4",
+                    "TnM": None,
+                    "TnS": None,
+                },
+            ),
+            (
+                "PT5M",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "5",
+                    "TnS": None,
+                },
+            ),
+            (
+                "PT6S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": None,
+                    "TnS": "6",
+                },
+            ),
+            (
+                "PT1H2M",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "1",
+                    "TnM": "2",
+                    "TnS": None,
+                },
+            ),
+            (
+                "PT3H4S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": "3",
+                    "TnM": None,
+                    "TnS": "4",
+                },
+            ),
+            (
+                "PT5M6S",
+                {
+                    "PnY": None,
+                    "PnM": None,
+                    "PnW": None,
+                    "PnD": None,
+                    "TnH": None,
+                    "TnM": "5",
+                    "TnS": "6",
+                },
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = _parse_duration_prescribed_time(testtuple[0])
+
+            self.assertEqual(result, testtuple[1])
+
+    def test_parse_duration_prescribed_time_timeindate(self):
+        # Don't allow time components in date half
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P1Y2M3D4HT54M6S")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P1Y2M3D6ST4H54M")
+
+    def test_parse_duration_prescribed_time_dateintime(self):
+        # Don't allow date components in time half
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P2M3DT1Y4H54M6S")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P1Y2MT3D4H54M6S")
+
+    def test_parse_duration_prescribed_time_outoforder(self):
+        # Ensure durations are required to be in the correct order
+        # https://bitbucket.org/nielsenb/aniso8601/issues/7/durations-with-time-components-before-t
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("1Y2M3D1SPT1M")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P1Y2M3D2MT1S")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P2M3D1ST1Y1M")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P1Y2M2MT3D1S")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("PT1S1H")
+
+    def test_parse_duration_prescribed_time_badstr(self):
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P1Y")
+
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_prescribed_time("P1Y1M")
+
+    def test_parse_duration_combined(self):
+        testtuples = (
+            (
+                "P0003-06-04T12:30:05",
+                {
+                    "PnY": "0003",
+                    "PnM": "06",
+                    "PnD": "04",
+                    "TnH": "12",
+                    "TnM": "30",
+                    "TnS": "05",
+                },
+            ),
+            (
+                "P0003-06-04T12:30:05,5",
+                {
+                    "PnY": "0003",
+                    "PnM": "06",
+                    "PnD": "04",
+                    "TnH": "12",
+                    "TnM": "30",
+                    "TnS": "05.5",
+                },
+            ),
+            (
+                "P0003-06-04T12:30:05.5",
+                {
+                    "PnY": "0003",
+                    "PnM": "06",
+                    "PnD": "04",
+                    "TnH": "12",
+                    "TnM": "30",
+                    "TnS": "05.5",
+                },
+            ),
+            (
+                "P0001-02-03T14:43:59.9999997",
+                {
+                    "PnY": "0001",
+                    "PnM": "02",
+                    "PnD": "03",
+                    "TnH": "14",
+                    "TnM": "43",
+                    "TnS": "59.9999997",
+                },
+            ),
+        )
+
+        for testtuple in testtuples:
+            result = _parse_duration_combined(testtuple[0])
+
+            self.assertEqual(result, testtuple[1])
+
+    def test_parse_duration_combined_suffixgarbage(self):
+        # Don't allow garbage after the duration
+        # https://bitbucket.org/nielsenb/aniso8601/issues/9/durations-with-trailing-garbage-are-parsed
+        with self.assertRaises(ISOFormatError):
+            _parse_duration_combined("P0003-06-04T12:30:05.5asdfasdf")
+
+    def test_has_any_component(self):
+        self.assertTrue(_has_any_component("P1Y", ["Y", "M"]))
+        self.assertFalse(_has_any_component("P1Y", ["M", "D"]))
diff --git a/libs/aniso8601/tests/test_init.py b/libs/aniso8601/tests/test_init.py
new file mode 100644
index 000000000..d5604c6b9
--- /dev/null
+++ b/libs/aniso8601/tests/test_init.py
@@ -0,0 +1,49 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+import aniso8601
+
+
+class TestInitFunctions(unittest.TestCase):
+    def test_import(self):
+        # Verify the function mappings
+        self.assertEqual(aniso8601.parse_datetime, aniso8601.time.parse_datetime)
+        self.assertEqual(aniso8601.parse_time, aniso8601.time.parse_time)
+        self.assertEqual(
+            aniso8601.get_time_resolution, aniso8601.time.get_time_resolution
+        )
+        self.assertEqual(
+            aniso8601.get_datetime_resolution, aniso8601.time.get_datetime_resolution
+        )
+
+        self.assertEqual(aniso8601.parse_date, aniso8601.date.parse_date)
+        self.assertEqual(
+            aniso8601.get_date_resolution, aniso8601.date.get_date_resolution
+        )
+
+        self.assertEqual(aniso8601.parse_duration, aniso8601.duration.parse_duration)
+        self.assertEqual(
+            aniso8601.get_duration_resolution,
+            aniso8601.duration.get_duration_resolution,
+        )
+
+        self.assertEqual(aniso8601.parse_interval, aniso8601.interval.parse_interval)
+        self.assertEqual(
+            aniso8601.parse_repeating_interval,
+            aniso8601.interval.parse_repeating_interval,
+        )
+        self.assertEqual(
+            aniso8601.get_interval_resolution,
+            aniso8601.interval.get_interval_resolution,
+        )
+        self.assertEqual(
+            aniso8601.get_repeating_interval_resolution,
+            aniso8601.interval.get_repeating_interval_resolution,
+        )
diff --git a/libs/aniso8601/tests/test_interval.py b/libs/aniso8601/tests/test_interval.py
new file mode 100644
index 000000000..f01d15112
--- /dev/null
+++ b/libs/aniso8601/tests/test_interval.py
@@ -0,0 +1,1675 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+import aniso8601
+from aniso8601.builders import (
+    DatetimeTuple,
+    DateTuple,
+    DurationTuple,
+    IntervalTuple,
+    TimeTuple,
+    TimezoneTuple,
+)
+from aniso8601.exceptions import ISOFormatError
+from aniso8601.interval import (
+    _get_interval_component_resolution,
+    _get_interval_resolution,
+    _parse_interval,
+    _parse_interval_end,
+    get_interval_resolution,
+    get_repeating_interval_resolution,
+    parse_interval,
+    parse_repeating_interval,
+)
+from aniso8601.resolution import IntervalResolution
+from aniso8601.tests.compat import mock
+
+
+class TestIntervalParser_UtilityFunctions(unittest.TestCase):
+    def test_get_interval_resolution(self):
+        self.assertEqual(
+            _get_interval_resolution(
+                IntervalTuple(
+                    start=DateTuple(
+                        YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                    ),
+                    end=DatetimeTuple(
+                        DateTuple(
+                            YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                        ),
+                        TimeTuple(hh="04", mm="05", ss="06", tz=None),
+                    ),
+                    duration=None,
+                )
+            ),
+            IntervalResolution.Seconds,
+        )
+        self.assertEqual(
+            _get_interval_resolution(
+                IntervalTuple(
+                    start=DatetimeTuple(
+                        DateTuple(
+                            YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                        ),
+                        TimeTuple(hh="04", mm="05", ss="06", tz=None),
+                    ),
+                    end=DateTuple(
+                        YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                    ),
+                    duration=None,
+                )
+            ),
+            IntervalResolution.Seconds,
+        )
+
+        self.assertEqual(
+            _get_interval_resolution(
+                IntervalTuple(
+                    start=DateTuple(
+                        YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                    ),
+                    end=None,
+                    duration=DurationTuple(
+                        PnY="1", PnM="2", PnW=None, PnD="3", TnH="4", TnM="5", TnS="6"
+                    ),
+                )
+            ),
+            IntervalResolution.Seconds,
+        )
+        self.assertEqual(
+            _get_interval_resolution(
+                IntervalTuple(
+                    start=DatetimeTuple(
+                        DateTuple(
+                            YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                        ),
+                        TimeTuple(hh="04", mm="05", ss="06", tz=None),
+                    ),
+                    end=None,
+                    duration=DurationTuple(
+                        PnY="1",
+                        PnM="2",
+                        PnW=None,
+                        PnD="3",
+                        TnH=None,
+                        TnM=None,
+                        TnS=None,
+                    ),
+                )
+            ),
+            IntervalResolution.Seconds,
+        )
+
+        self.assertEqual(
+            _get_interval_resolution(
+                IntervalTuple(
+                    start=None,
+                    end=DateTuple(
+                        YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                    ),
+                    duration=DurationTuple(
+                        PnY="1", PnM="2", PnW=None, PnD="3", TnH="4", TnM="5", TnS="6"
+                    ),
+                )
+            ),
+            IntervalResolution.Seconds,
+        )
+        self.assertEqual(
+            _get_interval_resolution(
+                IntervalTuple(
+                    start=None,
+                    end=DatetimeTuple(
+                        DateTuple(
+                            YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                        ),
+                        TimeTuple(hh="04", mm="05", ss="06", tz=None),
+                    ),
+                    duration=DurationTuple(
+                        PnY="1",
+                        PnM="2",
+                        PnW=None,
+                        PnD="3",
+                        TnH=None,
+                        TnM=None,
+                        TnS=None,
+                    ),
+                )
+            ),
+            IntervalResolution.Seconds,
+        )
+
+    def test_get_interval_component_resolution(self):
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DateTuple(YYYY="2001", MM=None, DD=None, Www=None, D=None, DDD="123")
+            ),
+            IntervalResolution.Ordinal,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DateTuple(YYYY="2001", MM=None, DD=None, Www="12", D="3", DDD=None)
+            ),
+            IntervalResolution.Weekday,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DateTuple(YYYY="2001", MM=None, DD=None, Www="12", D=None, DDD=None)
+            ),
+            IntervalResolution.Week,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DateTuple(YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None)
+            ),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DateTuple(YYYY="2001", MM="02", DD=None, Www=None, D=None, DDD=None)
+            ),
+            IntervalResolution.Month,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DateTuple(YYYY="2001", MM=None, DD=None, Www=None, D=None, DDD=None)
+            ),
+            IntervalResolution.Year,
+        )
+
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DatetimeTuple(
+                    DateTuple(
+                        YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                    ),
+                    TimeTuple(hh="04", mm="05", ss="06", tz=None),
+                )
+            ),
+            IntervalResolution.Seconds,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DatetimeTuple(
+                    DateTuple(
+                        YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                    ),
+                    TimeTuple(hh="04", mm="05", ss=None, tz=None),
+                )
+            ),
+            IntervalResolution.Minutes,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DatetimeTuple(
+                    DateTuple(
+                        YYYY="2001", MM="02", DD="03", Www=None, D=None, DDD=None
+                    ),
+                    TimeTuple(hh="04", mm=None, ss=None, tz=None),
+                )
+            ),
+            IntervalResolution.Hours,
+        )
+
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DurationTuple(
+                    PnY="1", PnM="2", PnW=None, PnD="3", TnH="4", TnM="5", TnS="6"
+                )
+            ),
+            IntervalResolution.Seconds,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DurationTuple(
+                    PnY="1", PnM="2", PnW=None, PnD="3", TnH="4", TnM="5", TnS=None
+                )
+            ),
+            IntervalResolution.Minutes,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DurationTuple(
+                    PnY="1", PnM="2", PnW=None, PnD="3", TnH="4", TnM=None, TnS=None
+                )
+            ),
+            IntervalResolution.Hours,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DurationTuple(
+                    PnY="1", PnM="2", PnW=None, PnD="3", TnH=None, TnM=None, TnS=None
+                )
+            ),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DurationTuple(
+                    PnY="1", PnM="2", PnW=None, PnD=None, TnH=None, TnM=None, TnS=None
+                )
+            ),
+            IntervalResolution.Month,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DurationTuple(
+                    PnY="1", PnM=None, PnW=None, PnD=None, TnH=None, TnM=None, TnS=None
+                )
+            ),
+            IntervalResolution.Year,
+        )
+        self.assertEqual(
+            _get_interval_component_resolution(
+                DurationTuple(
+                    PnY=None, PnM=None, PnW="3", PnD=None, TnH=None, TnM=None, TnS=None
+                )
+            ),
+            IntervalResolution.Week,
+        )
+
+
+class TestIntervalParserFunctions(unittest.TestCase):
+    def test_get_interval_resolution_date(self):
+        self.assertEqual(get_interval_resolution("P1.5Y/2018"), IntervalResolution.Year)
+        self.assertEqual(
+            get_interval_resolution("P1.5Y/2018-03"), IntervalResolution.Month
+        )
+        self.assertEqual(
+            get_interval_resolution("P1.5Y/2018-03-06"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("P1.5Y/2018W01"), IntervalResolution.Week
+        )
+        self.assertEqual(
+            get_interval_resolution("P1.5Y/2018-306"), IntervalResolution.Ordinal
+        )
+        self.assertEqual(
+            get_interval_resolution("P1.5Y/2018W012"), IntervalResolution.Weekday
+        )
+
+        self.assertEqual(get_interval_resolution("2018/P1.5Y"), IntervalResolution.Year)
+        self.assertEqual(
+            get_interval_resolution("2018-03/P1.5Y"), IntervalResolution.Month
+        )
+        self.assertEqual(
+            get_interval_resolution("2018-03-06/P1.5Y"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("2018W01/P1.5Y"), IntervalResolution.Week
+        )
+        self.assertEqual(
+            get_interval_resolution("2018-306/P1.5Y"), IntervalResolution.Ordinal
+        )
+        self.assertEqual(
+            get_interval_resolution("2018W012/P1.5Y"), IntervalResolution.Weekday
+        )
+
+    def test_get_interval_resolution_time(self):
+        self.assertEqual(
+            get_interval_resolution("P1M/1981-04-05T01"), IntervalResolution.Hours
+        )
+        self.assertEqual(
+            get_interval_resolution("P1M/1981-04-05T01:01"), IntervalResolution.Minutes
+        )
+        self.assertEqual(
+            get_interval_resolution("P1M/1981-04-05T01:01:00"),
+            IntervalResolution.Seconds,
+        )
+
+        self.assertEqual(
+            get_interval_resolution("1981-04-05T01/P1M"), IntervalResolution.Hours
+        )
+        self.assertEqual(
+            get_interval_resolution("1981-04-05T01:01/P1M"), IntervalResolution.Minutes
+        )
+        self.assertEqual(
+            get_interval_resolution("1981-04-05T01:01:00/P1M"),
+            IntervalResolution.Seconds,
+        )
+
+    def test_get_interval_resolution_duration(self):
+        self.assertEqual(
+            get_interval_resolution("2014-11-12/P1Y2M3D"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("2014-11-12/P1Y2M"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("2014-11-12/P1Y"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("2014-11-12/P1W"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("2014-11-12/P1Y2M3DT4H"), IntervalResolution.Hours
+        )
+        self.assertEqual(
+            get_interval_resolution("2014-11-12/P1Y2M3DT4H54M"),
+            IntervalResolution.Minutes,
+        )
+        self.assertEqual(
+            get_interval_resolution("2014-11-12/P1Y2M3DT4H54M6S"),
+            IntervalResolution.Seconds,
+        )
+
+        self.assertEqual(
+            get_interval_resolution("P1Y2M3D/2014-11-12"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("P1Y2M/2014-11-12"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("P1Y/2014-11-12"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("P1W/2014-11-12"), IntervalResolution.Day
+        )
+        self.assertEqual(
+            get_interval_resolution("P1Y2M3DT4H/2014-11-12"), IntervalResolution.Hours
+        )
+        self.assertEqual(
+            get_interval_resolution("P1Y2M3DT4H54M/2014-11-12"),
+            IntervalResolution.Minutes,
+        )
+        self.assertEqual(
+            get_interval_resolution("P1Y2M3DT4H54M6S/2014-11-12"),
+            IntervalResolution.Seconds,
+        )
+
+    def test_parse_interval(self):
+        testtuples = (
+            (
+                "P1M/1981-04-05T01:01:00",
+                {
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "duration": DurationTuple(None, "1", None, None, None, None, None),
+                },
+            ),
+            (
+                "P1M/1981-04-05",
+                {
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                    "duration": DurationTuple(None, "1", None, None, None, None, None),
+                },
+            ),
+            (
+                "P1,5Y/2018-03-06",
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        "1.5", None, None, None, None, None, None
+                    ),
+                },
+            ),
+            (
+                "P1.5Y/2018-03-06",
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        "1.5", None, None, None, None, None, None
+                    ),
+                },
+            ),
+            (
+                "PT1H/2014-11-12",
+                {
+                    "end": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "1", None, None),
+                },
+            ),
+            (
+                "PT4H54M6.5S/2014-11-12",
+                {
+                    "end": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "4", "54", "6.5"),
+                },
+            ),
+            (
+                "PT10H/2050-03-01T13:00:00Z",
+                {
+                    "end": DatetimeTuple(
+                        DateTuple("2050", "03", "01", None, None, None),
+                        TimeTuple(
+                            "13",
+                            "00",
+                            "00",
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "duration": DurationTuple(None, None, None, None, "10", None, None),
+                },
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                "PT0.0000001S/2018-03-06",
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "0.0000001"
+                    ),
+                },
+            ),
+            (
+                "PT2.0000048S/2018-03-06",
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "2.0000048"
+                    ),
+                },
+            ),
+            (
+                "1981-04-05T01:01:00/P1M1DT1M",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "duration": DurationTuple(None, "1", None, "1", None, "1", None),
+                },
+            ),
+            (
+                "1981-04-05/P1M1D",
+                {
+                    "start": DateTuple("1981", "04", "05", None, None, None),
+                    "duration": DurationTuple(None, "1", None, "1", None, None, None),
+                },
+            ),
+            (
+                "2018-03-06/P2,5M",
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, "2.5", None, None, None, None, None
+                    ),
+                },
+            ),
+            (
+                "2018-03-06/P2.5M",
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, "2.5", None, None, None, None, None
+                    ),
+                },
+            ),
+            (
+                "2014-11-12/PT1H",
+                {
+                    "start": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "1", None, None),
+                },
+            ),
+            (
+                "2014-11-12/PT4H54M6.5S",
+                {
+                    "start": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "4", "54", "6.5"),
+                },
+            ),
+            (
+                "2050-03-01T13:00:00Z/PT10H",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2050", "03", "01", None, None, None),
+                        TimeTuple(
+                            "13",
+                            "00",
+                            "00",
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "duration": DurationTuple(None, None, None, None, "10", None, None),
+                },
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                "2018-03-06/PT0.0000001S",
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "0.0000001"
+                    ),
+                },
+            ),
+            (
+                "2018-03-06/PT2.0000048S",
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "2.0000048"
+                    ),
+                },
+            ),
+            (
+                "1980-03-05T01:01:00/1981-04-05T01:01:00",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                },
+            ),
+            (
+                "1980-03-05T01:01:00/1981-04-05",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                },
+            ),
+            (
+                "1980-03-05/1981-04-05T01:01:00",
+                {
+                    "start": DateTuple("1980", "03", "05", None, None, None),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                },
+            ),
+            (
+                "1980-03-05/1981-04-05",
+                {
+                    "start": DateTuple("1980", "03", "05", None, None, None),
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                },
+            ),
+            (
+                "1981-04-05/1980-03-05",
+                {
+                    "start": DateTuple("1981", "04", "05", None, None, None),
+                    "end": DateTuple("1980", "03", "05", None, None, None),
+                },
+            ),
+            (
+                "2050-03-01T13:00:00Z/2050-05-11T15:30:00Z",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2050", "03", "01", None, None, None),
+                        TimeTuple(
+                            "13",
+                            "00",
+                            "00",
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("2050", "05", "11", None, None, None),
+                        TimeTuple(
+                            "15",
+                            "30",
+                            "00",
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                },
+            ),
+            # Test concise interval
+            (
+                "2020-01-01/02",
+                {
+                    "start": DateTuple("2020", "01", "01", None, None, None),
+                    "end": DateTuple(None, None, "02", None, None, None),
+                },
+            ),
+            (
+                "2008-02-15/03-14",
+                {
+                    "start": DateTuple("2008", "02", "15", None, None, None),
+                    "end": DateTuple(None, "03", "14", None, None, None),
+                },
+            ),
+            (
+                "2007-12-14T13:30/15:30",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "12", "14", None, None, None),
+                        TimeTuple("13", "30", None, None),
+                    ),
+                    "end": TimeTuple("15", "30", None, None),
+                },
+            ),
+            (
+                "2007-11-13T09:00/15T17:00",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("09", "00", None, None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "15", None, None, None),
+                        TimeTuple("17", "00", None, None),
+                    ),
+                },
+            ),
+            (
+                "2007-11-13T00:00/16T00:00",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("00", "00", None, None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "16", None, None, None),
+                        TimeTuple("00", "00", None, None),
+                    ),
+                },
+            ),
+            (
+                "2007-11-13T09:00Z/15T17:00",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple(
+                            "09",
+                            "00",
+                            None,
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "15", None, None, None),
+                        TimeTuple("17", "00", None, None),
+                    ),
+                },
+            ),
+            (
+                "2007-11-13T00:00/12:34.567",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("00", "00", None, None),
+                    ),
+                    "end": TimeTuple("12", "34.567", None, None),
+                },
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                "1980-03-05T01:01:00.0000001/" "1981-04-05T14:43:59.9999997",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00.0000001", None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("14", "43", "59.9999997", None),
+                    ),
+                },
+            ),
+        )
+
+        for testtuple in testtuples:
+            with mock.patch.object(
+                aniso8601.interval.PythonTimeBuilder, "build_interval"
+            ) as mockBuildInterval:
+                mockBuildInterval.return_value = testtuple[1]
+
+                result = parse_interval(testtuple[0])
+
+                self.assertEqual(result, testtuple[1])
+                mockBuildInterval.assert_called_once_with(**testtuple[1])
+
+        # Test different separators
+        with mock.patch.object(
+            aniso8601.interval.PythonTimeBuilder, "build_interval"
+        ) as mockBuildInterval:
+            expectedargs = {
+                "start": DatetimeTuple(
+                    DateTuple("1980", "03", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                "end": DatetimeTuple(
+                    DateTuple("1981", "04", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+            }
+
+            mockBuildInterval.return_value = expectedargs
+
+            result = parse_interval(
+                "1980-03-05T01:01:00--1981-04-05T01:01:00", intervaldelimiter="--"
+            )
+
+            self.assertEqual(result, expectedargs)
+            mockBuildInterval.assert_called_once_with(**expectedargs)
+
+        with mock.patch.object(
+            aniso8601.interval.PythonTimeBuilder, "build_interval"
+        ) as mockBuildInterval:
+            expectedargs = {
+                "start": DatetimeTuple(
+                    DateTuple("1980", "03", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                "end": DatetimeTuple(
+                    DateTuple("1981", "04", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+            }
+
+            mockBuildInterval.return_value = expectedargs
+
+            result = parse_interval(
+                "1980-03-05 01:01:00/1981-04-05 01:01:00", datetimedelimiter=" "
+            )
+
+            self.assertEqual(result, expectedargs)
+            mockBuildInterval.assert_called_once_with(**expectedargs)
+
+    def test_parse_interval_mockbuilder(self):
+        mockBuilder = mock.Mock()
+
+        expectedargs = {
+            "end": DatetimeTuple(
+                DateTuple("1981", "04", "05", None, None, None),
+                TimeTuple("01", "01", "00", None),
+            ),
+            "duration": DurationTuple(None, "1", None, None, None, None, None),
+        }
+
+        mockBuilder.build_interval.return_value = expectedargs
+
+        result = parse_interval("P1M/1981-04-05T01:01:00", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_interval.assert_called_once_with(**expectedargs)
+
+        mockBuilder = mock.Mock()
+
+        expectedargs = {
+            "start": DateTuple("2014", "11", "12", None, None, None),
+            "duration": DurationTuple(None, None, None, None, "1", None, None),
+        }
+
+        mockBuilder.build_interval.return_value = expectedargs
+
+        result = parse_interval("2014-11-12/PT1H", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_interval.assert_called_once_with(**expectedargs)
+
+        mockBuilder = mock.Mock()
+
+        expectedargs = {
+            "start": DatetimeTuple(
+                DateTuple("1980", "03", "05", None, None, None),
+                TimeTuple("01", "01", "00", None),
+            ),
+            "end": DatetimeTuple(
+                DateTuple("1981", "04", "05", None, None, None),
+                TimeTuple("01", "01", "00", None),
+            ),
+        }
+
+        mockBuilder.build_interval.return_value = expectedargs
+
+        result = parse_interval(
+            "1980-03-05T01:01:00/1981-04-05T01:01:00", builder=mockBuilder
+        )
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_interval.assert_called_once_with(**expectedargs)
+
+    def test_parse_interval_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                parse_interval(testtuple, builder=None)
+
+    def test_parse_interval_baddelimiter(self):
+        testtuples = (
+            "1980-03-05T01:01:00,1981-04-05T01:01:00",
+            "P1M 1981-04-05T01:01:00",
+        )
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_interval(testtuple, builder=None)
+
+    def test_parse_interval_badstr(self):
+        testtuples = ("/", "0/0/0", "20.50230/0", "5/%", "1/21", "bad", "")
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_interval(testtuple, builder=None)
+
+    def test_parse_interval_repeating(self):
+        # Parse interval can't parse repeating intervals
+        with self.assertRaises(ISOFormatError):
+            parse_interval("R3/1981-04-05/P1D")
+
+        with self.assertRaises(ISOFormatError):
+            parse_interval("R3/1981-04-05/P0003-06-04T12:30:05.5")
+
+        with self.assertRaises(ISOFormatError):
+            parse_interval("R/PT1H2M/1980-03-05T01:01:00")
+
+    def test_parse_interval_suffixgarbage(self):
+        # Don't allow garbage after the duration
+        # https://bitbucket.org/nielsenb/aniso8601/issues/9/durations-with-trailing-garbage-are-parsed
+        with self.assertRaises(ISOFormatError):
+            parse_interval("2001/P1Dasdf", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_interval("P1Dasdf/2001", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_interval("2001/P0003-06-04T12:30:05.5asdfasdf", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_interval("P0003-06-04T12:30:05.5asdfasdf/2001", builder=None)
+
+    def test_parse_interval_internal(self):
+        # Test the internal _parse_interval function
+        testtuples = (
+            (
+                "P1M/1981-04-05T01:01:00",
+                {
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "duration": DurationTuple(None, "1", None, None, None, None, None),
+                },
+            ),
+            (
+                "P1M/1981-04-05",
+                {
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                    "duration": DurationTuple(None, "1", None, None, None, None, None),
+                },
+            ),
+            (
+                "P1,5Y/2018-03-06",
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        "1.5", None, None, None, None, None, None
+                    ),
+                },
+            ),
+            (
+                "P1.5Y/2018-03-06",
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        "1.5", None, None, None, None, None, None
+                    ),
+                },
+            ),
+            (
+                "PT1H/2014-11-12",
+                {
+                    "end": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "1", None, None),
+                },
+            ),
+            (
+                "PT4H54M6.5S/2014-11-12",
+                {
+                    "end": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "4", "54", "6.5"),
+                },
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                "PT0.0000001S/2018-03-06",
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "0.0000001"
+                    ),
+                },
+            ),
+            (
+                "PT2.0000048S/2018-03-06",
+                {
+                    "end": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "2.0000048"
+                    ),
+                },
+            ),
+            (
+                "1981-04-05T01:01:00/P1M1DT1M",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "duration": DurationTuple(None, "1", None, "1", None, "1", None),
+                },
+            ),
+            (
+                "1981-04-05/P1M1D",
+                {
+                    "start": DateTuple("1981", "04", "05", None, None, None),
+                    "duration": DurationTuple(None, "1", None, "1", None, None, None),
+                },
+            ),
+            (
+                "2018-03-06/P2,5M",
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, "2.5", None, None, None, None, None
+                    ),
+                },
+            ),
+            (
+                "2018-03-06/P2.5M",
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, "2.5", None, None, None, None, None
+                    ),
+                },
+            ),
+            (
+                "2014-11-12/PT1H",
+                {
+                    "start": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "1", None, None),
+                },
+            ),
+            (
+                "2014-11-12/PT4H54M6.5S",
+                {
+                    "start": DateTuple("2014", "11", "12", None, None, None),
+                    "duration": DurationTuple(None, None, None, None, "4", "54", "6.5"),
+                },
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                "2018-03-06/PT0.0000001S",
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "0.0000001"
+                    ),
+                },
+            ),
+            (
+                "2018-03-06/PT2.0000048S",
+                {
+                    "start": DateTuple("2018", "03", "06", None, None, None),
+                    "duration": DurationTuple(
+                        None, None, None, None, None, None, "2.0000048"
+                    ),
+                },
+            ),
+            (
+                "1980-03-05T01:01:00/1981-04-05T01:01:00",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                },
+            ),
+            (
+                "1980-03-05T01:01:00/1981-04-05",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                },
+            ),
+            (
+                "1980-03-05/1981-04-05T01:01:00",
+                {
+                    "start": DateTuple("1980", "03", "05", None, None, None),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                },
+            ),
+            (
+                "1980-03-05/1981-04-05",
+                {
+                    "start": DateTuple("1980", "03", "05", None, None, None),
+                    "end": DateTuple("1981", "04", "05", None, None, None),
+                },
+            ),
+            (
+                "1981-04-05/1980-03-05",
+                {
+                    "start": DateTuple("1981", "04", "05", None, None, None),
+                    "end": DateTuple("1980", "03", "05", None, None, None),
+                },
+            ),
+            # Test concise interval
+            (
+                "2020-01-01/02",
+                {
+                    "start": DateTuple("2020", "01", "01", None, None, None),
+                    "end": DateTuple(None, None, "02", None, None, None),
+                },
+            ),
+            (
+                "2008-02-15/03-14",
+                {
+                    "start": DateTuple("2008", "02", "15", None, None, None),
+                    "end": DateTuple(None, "03", "14", None, None, None),
+                },
+            ),
+            (
+                "2007-12-14T13:30/15:30",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "12", "14", None, None, None),
+                        TimeTuple("13", "30", None, None),
+                    ),
+                    "end": TimeTuple("15", "30", None, None),
+                },
+            ),
+            (
+                "2007-11-13T09:00/15T17:00",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("09", "00", None, None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "15", None, None, None),
+                        TimeTuple("17", "00", None, None),
+                    ),
+                },
+            ),
+            (
+                "2007-11-13T00:00/16T00:00",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("00", "00", None, None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "16", None, None, None),
+                        TimeTuple("00", "00", None, None),
+                    ),
+                },
+            ),
+            (
+                "2007-11-13T09:00Z/15T17:00",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple(
+                            "09",
+                            "00",
+                            None,
+                            TimezoneTuple(False, True, None, None, "Z"),
+                        ),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple(None, None, "15", None, None, None),
+                        TimeTuple("17", "00", None, None),
+                    ),
+                },
+            ),
+            (
+                "2007-11-13T00:00/12:34.567",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("2007", "11", "13", None, None, None),
+                        TimeTuple("00", "00", None, None),
+                    ),
+                    "end": TimeTuple("12", "34.567", None, None),
+                },
+            ),
+            # Make sure we truncate, not round
+            # https://bitbucket.org/nielsenb/aniso8601/issues/10/sub-microsecond-precision-in-durations-is
+            (
+                "1980-03-05T01:01:00.0000001/" "1981-04-05T14:43:59.9999997",
+                {
+                    "start": DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00.0000001", None),
+                    ),
+                    "end": DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("14", "43", "59.9999997", None),
+                    ),
+                },
+            ),
+        )
+
+        for testtuple in testtuples:
+            mockBuilder = mock.Mock()
+            mockBuilder.build_interval.return_value = testtuple[1]
+
+            result = _parse_interval(testtuple[0], mockBuilder)
+
+            self.assertEqual(result, testtuple[1])
+            mockBuilder.build_interval.assert_called_once_with(**testtuple[1])
+
+        # Test different separators
+        expectedargs = {
+            "start": DatetimeTuple(
+                DateTuple("1980", "03", "05", None, None, None),
+                TimeTuple("01", "01", "00", None),
+            ),
+            "end": DatetimeTuple(
+                DateTuple("1981", "04", "05", None, None, None),
+                TimeTuple("01", "01", "00", None),
+            ),
+        }
+
+        mockBuilder = mock.Mock()
+        mockBuilder.build_interval.return_value = expectedargs
+
+        result = _parse_interval(
+            "1980-03-05T01:01:00--1981-04-05T01:01:00",
+            mockBuilder,
+            intervaldelimiter="--",
+        )
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_interval.assert_called_once_with(**expectedargs)
+
+        expectedargs = {
+            "start": DatetimeTuple(
+                DateTuple("1980", "03", "05", None, None, None),
+                TimeTuple("01", "01", "00", None),
+            ),
+            "end": DatetimeTuple(
+                DateTuple("1981", "04", "05", None, None, None),
+                TimeTuple("01", "01", "00", None),
+            ),
+        }
+
+        mockBuilder = mock.Mock()
+        mockBuilder.build_interval.return_value = expectedargs
+
+        _parse_interval(
+            "1980-03-05 01:01:00/1981-04-05 01:01:00",
+            mockBuilder,
+            datetimedelimiter=" ",
+        )
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_interval.assert_called_once_with(**expectedargs)
+
+    def test_parse_interval_end(self):
+        self.assertEqual(
+            _parse_interval_end(
+                "02", DateTuple("2020", "01", "01", None, None, None), "T"
+            ),
+            DateTuple(None, None, "02", None, None, None),
+        )
+
+        self.assertEqual(
+            _parse_interval_end(
+                "03-14", DateTuple("2008", "02", "15", None, None, None), "T"
+            ),
+            DateTuple(None, "03", "14", None, None, None),
+        )
+
+        self.assertEqual(
+            _parse_interval_end(
+                "0314", DateTuple("2008", "02", "15", None, None, None), "T"
+            ),
+            DateTuple(None, "03", "14", None, None, None),
+        )
+
+        self.assertEqual(
+            _parse_interval_end(
+                "15:30",
+                DatetimeTuple(
+                    DateTuple("2007", "12", "14", None, None, None),
+                    TimeTuple("13", "30", None, None),
+                ),
+                "T",
+            ),
+            TimeTuple("15", "30", None, None),
+        )
+
+        self.assertEqual(
+            _parse_interval_end(
+                "15T17:00",
+                DatetimeTuple(
+                    DateTuple("2007", "11", "13", None, None, None),
+                    TimeTuple("09", "00", None, None),
+                ),
+                "T",
+            ),
+            DatetimeTuple(
+                DateTuple(None, None, "15", None, None, None),
+                TimeTuple("17", "00", None, None),
+            ),
+        )
+
+        self.assertEqual(
+            _parse_interval_end(
+                "16T00:00",
+                DatetimeTuple(
+                    DateTuple("2007", "11", "13", None, None, None),
+                    TimeTuple("00", "00", None, None),
+                ),
+                "T",
+            ),
+            DatetimeTuple(
+                DateTuple(None, None, "16", None, None, None),
+                TimeTuple("00", "00", None, None),
+            ),
+        )
+
+        self.assertEqual(
+            _parse_interval_end(
+                "15 17:00",
+                DatetimeTuple(
+                    DateTuple("2007", "11", "13", None, None, None),
+                    TimeTuple("09", "00", None, None),
+                ),
+                " ",
+            ),
+            DatetimeTuple(
+                DateTuple(None, None, "15", None, None, None),
+                TimeTuple("17", "00", None, None),
+            ),
+        )
+
+        self.assertEqual(
+            _parse_interval_end(
+                "12:34.567",
+                DatetimeTuple(
+                    DateTuple("2007", "11", "13", None, None, None),
+                    TimeTuple("00", "00", None, None),
+                ),
+                "T",
+            ),
+            TimeTuple("12", "34.567", None, None),
+        )
+
+
+class TestRepeatingIntervalParserFunctions(unittest.TestCase):
+    def test_get_interval_resolution_date(self):
+        self.assertEqual(
+            get_repeating_interval_resolution("R/P1.5Y/2018"), IntervalResolution.Year
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R1/P1.5Y/2018-03"),
+            IntervalResolution.Month,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R2/P1.5Y/2018-03-06"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R3/P1.5Y/2018W01"),
+            IntervalResolution.Week,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R4/P1.5Y/2018-306"),
+            IntervalResolution.Ordinal,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R5/P1.5Y/2018W012"),
+            IntervalResolution.Weekday,
+        )
+
+        self.assertEqual(
+            get_repeating_interval_resolution("R/2018/P1.5Y"), IntervalResolution.Year
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R1/2018-03/P1.5Y"),
+            IntervalResolution.Month,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R2/2018-03-06/P1.5Y"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R3/2018W01/P1.5Y"),
+            IntervalResolution.Week,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R4/2018-306/P1.5Y"),
+            IntervalResolution.Ordinal,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R5/2018W012/P1.5Y"),
+            IntervalResolution.Weekday,
+        )
+
+    def test_get_interval_resolution_time(self):
+        self.assertEqual(
+            get_repeating_interval_resolution("R/P1M/1981-04-05T01"),
+            IntervalResolution.Hours,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R1/P1M/1981-04-05T01:01"),
+            IntervalResolution.Minutes,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R2/P1M/1981-04-05T01:01:00"),
+            IntervalResolution.Seconds,
+        )
+
+        self.assertEqual(
+            get_repeating_interval_resolution("R/1981-04-05T01/P1M"),
+            IntervalResolution.Hours,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R1/1981-04-05T01:01/P1M"),
+            IntervalResolution.Minutes,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R2/1981-04-05T01:01:00/P1M"),
+            IntervalResolution.Seconds,
+        )
+
+    def test_get_interval_resolution_duration(self):
+        self.assertEqual(
+            get_repeating_interval_resolution("R/2014-11-12/P1Y2M3D"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R1/2014-11-12/P1Y2M"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R2/2014-11-12/P1Y"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R3/2014-11-12/P1W"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R4/2014-11-12/P1Y2M3DT4H"),
+            IntervalResolution.Hours,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R5/2014-11-12/P1Y2M3DT4H54M"),
+            IntervalResolution.Minutes,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R6/2014-11-12/P1Y2M3DT4H54M6S"),
+            IntervalResolution.Seconds,
+        )
+
+        self.assertEqual(
+            get_repeating_interval_resolution("R/P1Y2M3D/2014-11-12"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R1/P1Y2M/2014-11-12"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R2/P1Y/2014-11-12"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R3/P1W/2014-11-12"),
+            IntervalResolution.Day,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R4/P1Y2M3DT4H/2014-11-12"),
+            IntervalResolution.Hours,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R5/P1Y2M3DT4H54M/2014-11-12"),
+            IntervalResolution.Minutes,
+        )
+        self.assertEqual(
+            get_repeating_interval_resolution("R6/P1Y2M3DT4H54M6S/2014-11-12"),
+            IntervalResolution.Seconds,
+        )
+
+    def test_parse_repeating_interval(self):
+        with mock.patch.object(
+            aniso8601.interval.PythonTimeBuilder, "build_repeating_interval"
+        ) as mockBuilder:
+            expectedargs = {
+                "R": False,
+                "Rnn": "3",
+                "interval": IntervalTuple(
+                    DateTuple("1981", "04", "05", None, None, None),
+                    None,
+                    DurationTuple(None, None, None, "1", None, None, None),
+                ),
+            }
+
+            mockBuilder.return_value = expectedargs
+
+            result = parse_repeating_interval("R3/1981-04-05/P1D")
+
+            self.assertEqual(result, expectedargs)
+            mockBuilder.assert_called_once_with(**expectedargs)
+
+        with mock.patch.object(
+            aniso8601.interval.PythonTimeBuilder, "build_repeating_interval"
+        ) as mockBuilder:
+            expectedargs = {
+                "R": False,
+                "Rnn": "11",
+                "interval": IntervalTuple(
+                    None,
+                    DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    DurationTuple(None, None, None, None, "1", "2", None),
+                ),
+            }
+
+            mockBuilder.return_value = expectedargs
+
+            result = parse_repeating_interval("R11/PT1H2M/1980-03-05T01:01:00")
+
+            self.assertEqual(result, expectedargs)
+            mockBuilder.assert_called_once_with(**expectedargs)
+
+        with mock.patch.object(
+            aniso8601.interval.PythonTimeBuilder, "build_repeating_interval"
+        ) as mockBuilder:
+            expectedargs = {
+                "R": False,
+                "Rnn": "2",
+                "interval": IntervalTuple(
+                    DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    None,
+                ),
+            }
+
+            mockBuilder.return_value = expectedargs
+
+            result = parse_repeating_interval(
+                "R2--1980-03-05T01:01:00--" "1981-04-05T01:01:00",
+                intervaldelimiter="--",
+            )
+
+            self.assertEqual(result, expectedargs)
+            mockBuilder.assert_called_once_with(**expectedargs)
+
+        with mock.patch.object(
+            aniso8601.interval.PythonTimeBuilder, "build_repeating_interval"
+        ) as mockBuilder:
+            expectedargs = {
+                "R": False,
+                "Rnn": "2",
+                "interval": IntervalTuple(
+                    DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    DatetimeTuple(
+                        DateTuple("1981", "04", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    None,
+                ),
+            }
+
+            mockBuilder.return_value = expectedargs
+
+            result = parse_repeating_interval(
+                "R2/" "1980-03-05 01:01:00/" "1981-04-05 01:01:00",
+                datetimedelimiter=" ",
+            )
+
+            self.assertEqual(result, expectedargs)
+            mockBuilder.assert_called_once_with(**expectedargs)
+
+        with mock.patch.object(
+            aniso8601.interval.PythonTimeBuilder, "build_repeating_interval"
+        ) as mockBuilder:
+            expectedargs = {
+                "R": True,
+                "Rnn": None,
+                "interval": IntervalTuple(
+                    None,
+                    DatetimeTuple(
+                        DateTuple("1980", "03", "05", None, None, None),
+                        TimeTuple("01", "01", "00", None),
+                    ),
+                    DurationTuple(None, None, None, None, "1", "2", None),
+                ),
+            }
+
+            mockBuilder.return_value = expectedargs
+
+            result = parse_repeating_interval("R/PT1H2M/1980-03-05T01:01:00")
+
+            self.assertEqual(result, expectedargs)
+            mockBuilder.assert_called_once_with(**expectedargs)
+
+    def test_parse_repeating_interval_mockbuilder(self):
+        mockBuilder = mock.Mock()
+
+        args = {
+            "R": False,
+            "Rnn": "3",
+            "interval": IntervalTuple(
+                DateTuple("1981", "04", "05", None, None, None),
+                None,
+                DurationTuple(None, None, None, "1", None, None, None),
+            ),
+        }
+
+        mockBuilder.build_repeating_interval.return_value = args
+
+        result = parse_repeating_interval("R3/1981-04-05/P1D", builder=mockBuilder)
+
+        self.assertEqual(result, args)
+        mockBuilder.build_repeating_interval.assert_called_once_with(**args)
+
+        mockBuilder = mock.Mock()
+
+        args = {
+            "R": False,
+            "Rnn": "11",
+            "interval": IntervalTuple(
+                None,
+                DatetimeTuple(
+                    DateTuple("1980", "03", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                DurationTuple(None, None, None, None, "1", "2", None),
+            ),
+        }
+
+        mockBuilder.build_repeating_interval.return_value = args
+
+        result = parse_repeating_interval(
+            "R11/PT1H2M/1980-03-05T01:01:00", builder=mockBuilder
+        )
+
+        self.assertEqual(result, args)
+        mockBuilder.build_repeating_interval.assert_called_once_with(**args)
+
+        mockBuilder = mock.Mock()
+
+        args = {
+            "R": True,
+            "Rnn": None,
+            "interval": IntervalTuple(
+                None,
+                DatetimeTuple(
+                    DateTuple("1980", "03", "05", None, None, None),
+                    TimeTuple("01", "01", "00", None),
+                ),
+                DurationTuple(None, None, None, None, "1", "2", None),
+            ),
+        }
+
+        mockBuilder.build_repeating_interval.return_value = args
+
+        result = parse_repeating_interval(
+            "R/PT1H2M/1980-03-05T01:01:00", builder=mockBuilder
+        )
+
+        self.assertEqual(result, args)
+        mockBuilder.build_repeating_interval.assert_called_once_with(**args)
+
+    def test_parse_repeating_interval_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                parse_repeating_interval(testtuple, builder=None)
+
+    def test_parse_repeating_interval_baddelimiter(self):
+        testtuples = ("R,PT1H2M,1980-03-05T01:01:00", "R3 1981-04-05 P1D")
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_repeating_interval(testtuple, builder=None)
+
+    def test_parse_repeating_interval_suffixgarbage(self):
+        # Don't allow garbage after the duration
+        # https://bitbucket.org/nielsenb/aniso8601/issues/9/durations-with-trailing-garbage-are-parsed
+        with self.assertRaises(ISOFormatError):
+            parse_repeating_interval("R3/1981-04-05/P1Dasdf", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_repeating_interval(
+                "R3/" "1981-04-05/" "P0003-06-04T12:30:05.5asdfasdf", builder=None
+            )
+
+    def test_parse_repeating_interval_badstr(self):
+        testtuples = ("bad", "")
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_repeating_interval(testtuple, builder=None)
diff --git a/libs/aniso8601/tests/test_time.py b/libs/aniso8601/tests/test_time.py
new file mode 100644
index 000000000..dcee5e03f
--- /dev/null
+++ b/libs/aniso8601/tests/test_time.py
@@ -0,0 +1,539 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+import aniso8601
+from aniso8601.builders import DatetimeTuple, DateTuple, TimeTuple, TimezoneTuple
+from aniso8601.exceptions import ISOFormatError
+from aniso8601.resolution import TimeResolution
+from aniso8601.tests.compat import mock
+from aniso8601.time import (
+    _get_time_resolution,
+    get_datetime_resolution,
+    get_time_resolution,
+    parse_datetime,
+    parse_time,
+)
+
+
+class TestTimeResolutionFunctions(unittest.TestCase):
+    def test_get_time_resolution(self):
+        self.assertEqual(get_time_resolution("01:23:45"), TimeResolution.Seconds)
+        self.assertEqual(get_time_resolution("24:00:00"), TimeResolution.Seconds)
+        self.assertEqual(get_time_resolution("23:21:28,512400"), TimeResolution.Seconds)
+        self.assertEqual(get_time_resolution("23:21:28.512400"), TimeResolution.Seconds)
+        self.assertEqual(get_time_resolution("01:23"), TimeResolution.Minutes)
+        self.assertEqual(get_time_resolution("24:00"), TimeResolution.Minutes)
+        self.assertEqual(get_time_resolution("01:23,4567"), TimeResolution.Minutes)
+        self.assertEqual(get_time_resolution("01:23.4567"), TimeResolution.Minutes)
+        self.assertEqual(get_time_resolution("012345"), TimeResolution.Seconds)
+        self.assertEqual(get_time_resolution("240000"), TimeResolution.Seconds)
+        self.assertEqual(get_time_resolution("0123"), TimeResolution.Minutes)
+        self.assertEqual(get_time_resolution("2400"), TimeResolution.Minutes)
+        self.assertEqual(get_time_resolution("01"), TimeResolution.Hours)
+        self.assertEqual(get_time_resolution("24"), TimeResolution.Hours)
+        self.assertEqual(get_time_resolution("12,5"), TimeResolution.Hours)
+        self.assertEqual(get_time_resolution("12.5"), TimeResolution.Hours)
+        self.assertEqual(
+            get_time_resolution("232128.512400+00:00"), TimeResolution.Seconds
+        )
+        self.assertEqual(get_time_resolution("0123.4567+00:00"), TimeResolution.Minutes)
+        self.assertEqual(get_time_resolution("01.4567+00:00"), TimeResolution.Hours)
+        self.assertEqual(get_time_resolution("01:23:45+00:00"), TimeResolution.Seconds)
+        self.assertEqual(get_time_resolution("24:00:00+00:00"), TimeResolution.Seconds)
+        self.assertEqual(
+            get_time_resolution("23:21:28.512400+00:00"), TimeResolution.Seconds
+        )
+        self.assertEqual(get_time_resolution("01:23+00:00"), TimeResolution.Minutes)
+        self.assertEqual(get_time_resolution("24:00+00:00"), TimeResolution.Minutes)
+        self.assertEqual(
+            get_time_resolution("01:23.4567+00:00"), TimeResolution.Minutes
+        )
+        self.assertEqual(
+            get_time_resolution("23:21:28.512400+11:15"), TimeResolution.Seconds
+        )
+        self.assertEqual(
+            get_time_resolution("23:21:28.512400-12:34"), TimeResolution.Seconds
+        )
+        self.assertEqual(
+            get_time_resolution("23:21:28.512400Z"), TimeResolution.Seconds
+        )
+        self.assertEqual(
+            get_time_resolution("06:14:00.000123Z"), TimeResolution.Seconds
+        )
+
+    def test_get_datetime_resolution(self):
+        self.assertEqual(
+            get_datetime_resolution("2019-06-05T01:03:11.858714"),
+            TimeResolution.Seconds,
+        )
+        self.assertEqual(
+            get_datetime_resolution("2019-06-05T01:03:11"), TimeResolution.Seconds
+        )
+        self.assertEqual(
+            get_datetime_resolution("2019-06-05T01:03"), TimeResolution.Minutes
+        )
+        self.assertEqual(get_datetime_resolution("2019-06-05T01"), TimeResolution.Hours)
+
+    def test_get_time_resolution_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                get_time_resolution(testtuple)
+
+    def test_get_time_resolution_badstr(self):
+        testtuples = ("A6:14:00.000123Z", "06:14:0B", "bad", "")
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                get_time_resolution(testtuple)
+
+    def test_get_time_resolution_internal(self):
+        self.assertEqual(
+            _get_time_resolution(TimeTuple(hh="01", mm="02", ss="03", tz=None)),
+            TimeResolution.Seconds,
+        )
+        self.assertEqual(
+            _get_time_resolution(TimeTuple(hh="01", mm="02", ss=None, tz=None)),
+            TimeResolution.Minutes,
+        )
+        self.assertEqual(
+            _get_time_resolution(TimeTuple(hh="01", mm=None, ss=None, tz=None)),
+            TimeResolution.Hours,
+        )
+
+
+class TestTimeParserFunctions(unittest.TestCase):
+    def test_parse_time(self):
+        testtuples = (
+            ("01:23:45", {"hh": "01", "mm": "23", "ss": "45", "tz": None}),
+            ("24:00:00", {"hh": "24", "mm": "00", "ss": "00", "tz": None}),
+            (
+                "23:21:28,512400",
+                {"hh": "23", "mm": "21", "ss": "28.512400", "tz": None},
+            ),
+            (
+                "23:21:28.512400",
+                {"hh": "23", "mm": "21", "ss": "28.512400", "tz": None},
+            ),
+            (
+                "01:03:11.858714",
+                {"hh": "01", "mm": "03", "ss": "11.858714", "tz": None},
+            ),
+            (
+                "14:43:59.9999997",
+                {"hh": "14", "mm": "43", "ss": "59.9999997", "tz": None},
+            ),
+            ("01:23", {"hh": "01", "mm": "23", "ss": None, "tz": None}),
+            ("24:00", {"hh": "24", "mm": "00", "ss": None, "tz": None}),
+            ("01:23,4567", {"hh": "01", "mm": "23.4567", "ss": None, "tz": None}),
+            ("01:23.4567", {"hh": "01", "mm": "23.4567", "ss": None, "tz": None}),
+            ("012345", {"hh": "01", "mm": "23", "ss": "45", "tz": None}),
+            ("240000", {"hh": "24", "mm": "00", "ss": "00", "tz": None}),
+            ("232128,512400", {"hh": "23", "mm": "21", "ss": "28.512400", "tz": None}),
+            ("232128.512400", {"hh": "23", "mm": "21", "ss": "28.512400", "tz": None}),
+            ("010311.858714", {"hh": "01", "mm": "03", "ss": "11.858714", "tz": None}),
+            (
+                "144359.9999997",
+                {"hh": "14", "mm": "43", "ss": "59.9999997", "tz": None},
+            ),
+            ("0123", {"hh": "01", "mm": "23", "ss": None, "tz": None}),
+            ("2400", {"hh": "24", "mm": "00", "ss": None, "tz": None}),
+            ("01", {"hh": "01", "mm": None, "ss": None, "tz": None}),
+            ("24", {"hh": "24", "mm": None, "ss": None, "tz": None}),
+            ("12,5", {"hh": "12.5", "mm": None, "ss": None, "tz": None}),
+            ("12.5", {"hh": "12.5", "mm": None, "ss": None, "tz": None}),
+            (
+                "232128,512400+00:00",
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "232128.512400+00:00",
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "0123,4567+00:00",
+                {
+                    "hh": "01",
+                    "mm": "23.4567",
+                    "ss": None,
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "0123.4567+00:00",
+                {
+                    "hh": "01",
+                    "mm": "23.4567",
+                    "ss": None,
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "01,4567+00:00",
+                {
+                    "hh": "01.4567",
+                    "mm": None,
+                    "ss": None,
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "01.4567+00:00",
+                {
+                    "hh": "01.4567",
+                    "mm": None,
+                    "ss": None,
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "01:23:45+00:00",
+                {
+                    "hh": "01",
+                    "mm": "23",
+                    "ss": "45",
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "24:00:00+00:00",
+                {
+                    "hh": "24",
+                    "mm": "00",
+                    "ss": "00",
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "23:21:28.512400+00:00",
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "01:23+00:00",
+                {
+                    "hh": "01",
+                    "mm": "23",
+                    "ss": None,
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "24:00+00:00",
+                {
+                    "hh": "24",
+                    "mm": "00",
+                    "ss": None,
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "01:23.4567+00:00",
+                {
+                    "hh": "01",
+                    "mm": "23.4567",
+                    "ss": None,
+                    "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+                },
+            ),
+            (
+                "23:21:28.512400+11:15",
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, None, "11", "15", "+11:15"),
+                },
+            ),
+            (
+                "23:21:28.512400-12:34",
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(True, None, "12", "34", "-12:34"),
+                },
+            ),
+            (
+                "23:21:28.512400Z",
+                {
+                    "hh": "23",
+                    "mm": "21",
+                    "ss": "28.512400",
+                    "tz": TimezoneTuple(False, True, None, None, "Z"),
+                },
+            ),
+            (
+                "06:14:00.000123Z",
+                {
+                    "hh": "06",
+                    "mm": "14",
+                    "ss": "00.000123",
+                    "tz": TimezoneTuple(False, True, None, None, "Z"),
+                },
+            ),
+        )
+
+        for testtuple in testtuples:
+            with mock.patch.object(
+                aniso8601.time.PythonTimeBuilder, "build_time"
+            ) as mockBuildTime:
+
+                mockBuildTime.return_value = testtuple[1]
+
+                result = parse_time(testtuple[0])
+
+                self.assertEqual(result, testtuple[1])
+                mockBuildTime.assert_called_once_with(**testtuple[1])
+
+    def test_parse_time_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                parse_time(testtuple, builder=None)
+
+    def test_parse_time_badstr(self):
+        testtuples = (
+            "A6:14:00.000123Z",
+            "06:14:0B",
+            "06:1 :02",
+            "0000,70:24,9",
+            "00.27:5332",
+            "bad",
+            "",
+        )
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_time(testtuple, builder=None)
+
+    def test_parse_time_mockbuilder(self):
+        mockBuilder = mock.Mock()
+
+        expectedargs = {"hh": "01", "mm": "23", "ss": "45", "tz": None}
+
+        mockBuilder.build_time.return_value = expectedargs
+
+        result = parse_time("01:23:45", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_time.assert_called_once_with(**expectedargs)
+
+        mockBuilder = mock.Mock()
+
+        expectedargs = {
+            "hh": "23",
+            "mm": "21",
+            "ss": "28.512400",
+            "tz": TimezoneTuple(False, None, "00", "00", "+00:00"),
+        }
+
+        mockBuilder.build_time.return_value = expectedargs
+
+        result = parse_time("232128.512400+00:00", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_time.assert_called_once_with(**expectedargs)
+
+        mockBuilder = mock.Mock()
+
+        expectedargs = {
+            "hh": "23",
+            "mm": "21",
+            "ss": "28.512400",
+            "tz": TimezoneTuple(False, None, "11", "15", "+11:15"),
+        }
+
+        mockBuilder.build_time.return_value = expectedargs
+
+        result = parse_time("23:21:28.512400+11:15", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_time.assert_called_once_with(**expectedargs)
+
+    def test_parse_datetime(self):
+        testtuples = (
+            (
+                "2019-06-05T01:03:11,858714",
+                (
+                    DateTuple("2019", "06", "05", None, None, None),
+                    TimeTuple("01", "03", "11.858714", None),
+                ),
+            ),
+            (
+                "2019-06-05T01:03:11.858714",
+                (
+                    DateTuple("2019", "06", "05", None, None, None),
+                    TimeTuple("01", "03", "11.858714", None),
+                ),
+            ),
+            (
+                "1981-04-05T23:21:28.512400Z",
+                (
+                    DateTuple("1981", "04", "05", None, None, None),
+                    TimeTuple(
+                        "23",
+                        "21",
+                        "28.512400",
+                        TimezoneTuple(False, True, None, None, "Z"),
+                    ),
+                ),
+            ),
+            (
+                "1981095T23:21:28.512400-12:34",
+                (
+                    DateTuple("1981", None, None, None, None, "095"),
+                    TimeTuple(
+                        "23",
+                        "21",
+                        "28.512400",
+                        TimezoneTuple(True, None, "12", "34", "-12:34"),
+                    ),
+                ),
+            ),
+            (
+                "19810405T23:21:28+00",
+                (
+                    DateTuple("1981", "04", "05", None, None, None),
+                    TimeTuple(
+                        "23", "21", "28", TimezoneTuple(False, None, "00", None, "+00")
+                    ),
+                ),
+            ),
+            (
+                "19810405T23:21:28+00:00",
+                (
+                    DateTuple("1981", "04", "05", None, None, None),
+                    TimeTuple(
+                        "23",
+                        "21",
+                        "28",
+                        TimezoneTuple(False, None, "00", "00", "+00:00"),
+                    ),
+                ),
+            ),
+        )
+
+        for testtuple in testtuples:
+            with mock.patch.object(
+                aniso8601.time.PythonTimeBuilder, "build_datetime"
+            ) as mockBuildDateTime:
+
+                mockBuildDateTime.return_value = testtuple[1]
+
+                result = parse_datetime(testtuple[0])
+
+            self.assertEqual(result, testtuple[1])
+            mockBuildDateTime.assert_called_once_with(*testtuple[1])
+
+    def test_parse_datetime_spacedelimited(self):
+        expectedargs = (
+            DateTuple("2004", None, None, "53", "6", None),
+            TimeTuple(
+                "23", "21", "28.512400", TimezoneTuple(True, None, "12", "34", "-12:34")
+            ),
+        )
+
+        with mock.patch.object(
+            aniso8601.time.PythonTimeBuilder, "build_datetime"
+        ) as mockBuildDateTime:
+
+            mockBuildDateTime.return_value = expectedargs
+
+            result = parse_datetime("2004-W53-6 23:21:28.512400-12:34", delimiter=" ")
+
+        self.assertEqual(result, expectedargs)
+        mockBuildDateTime.assert_called_once_with(*expectedargs)
+
+    def test_parse_datetime_commadelimited(self):
+        expectedargs = (
+            DateTuple("1981", "04", "05", None, None, None),
+            TimeTuple(
+                "23", "21", "28.512400", TimezoneTuple(False, True, None, None, "Z")
+            ),
+        )
+
+        with mock.patch.object(
+            aniso8601.time.PythonTimeBuilder, "build_datetime"
+        ) as mockBuildDateTime:
+
+            mockBuildDateTime.return_value = expectedargs
+
+            result = parse_datetime("1981-04-05,23:21:28,512400Z", delimiter=",")
+
+        self.assertEqual(result, expectedargs)
+        mockBuildDateTime.assert_called_once_with(*expectedargs)
+
+    def test_parse_datetime_baddelimiter(self):
+        testtuples = (
+            "1981-04-05,23:21:28,512400Z",
+            "2004-W53-6 23:21:28.512400-12:3",
+            "1981040523:21:28",
+        )
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_datetime(testtuple, builder=None)
+
+    def test_parse_datetime_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                parse_datetime(testtuple, builder=None)
+
+    def test_parse_datetime_badstr(self):
+        testtuples = (
+            "1981-04-05TA6:14:00.000123Z",
+            "2004-W53-6T06:14:0B",
+            "2014-01-230T23:21:28+00",
+            "201401230T01:03:11.858714",
+            "9999 W53T49",
+            "9T0000,70:24,9",
+            "bad",
+            "",
+        )
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_datetime(testtuple, builder=None)
+
+    def test_parse_datetime_mockbuilder(self):
+        mockBuilder = mock.Mock()
+
+        expectedargs = (
+            DateTuple("1981", None, None, None, None, "095"),
+            TimeTuple(
+                "23", "21", "28.512400", TimezoneTuple(True, None, "12", "34", "-12:34")
+            ),
+        )
+
+        mockBuilder.build_datetime.return_value = expectedargs
+
+        result = parse_datetime("1981095T23:21:28.512400-12:34", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_datetime.assert_called_once_with(*expectedargs)
diff --git a/libs/aniso8601/tests/test_timezone.py b/libs/aniso8601/tests/test_timezone.py
new file mode 100644
index 000000000..5df9671f1
--- /dev/null
+++ b/libs/aniso8601/tests/test_timezone.py
@@ -0,0 +1,123 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import unittest
+
+import aniso8601
+from aniso8601.exceptions import ISOFormatError
+from aniso8601.tests.compat import mock
+from aniso8601.timezone import parse_timezone
+
+
+class TestTimezoneParserFunctions(unittest.TestCase):
+    def test_parse_timezone(self):
+        testtuples = (
+            ("Z", {"negative": False, "Z": True, "name": "Z"}),
+            ("+00:00", {"negative": False, "hh": "00", "mm": "00", "name": "+00:00"}),
+            ("+01:00", {"negative": False, "hh": "01", "mm": "00", "name": "+01:00"}),
+            ("-01:00", {"negative": True, "hh": "01", "mm": "00", "name": "-01:00"}),
+            ("+00:12", {"negative": False, "hh": "00", "mm": "12", "name": "+00:12"}),
+            ("+01:23", {"negative": False, "hh": "01", "mm": "23", "name": "+01:23"}),
+            ("-01:23", {"negative": True, "hh": "01", "mm": "23", "name": "-01:23"}),
+            ("+0000", {"negative": False, "hh": "00", "mm": "00", "name": "+0000"}),
+            ("+0100", {"negative": False, "hh": "01", "mm": "00", "name": "+0100"}),
+            ("-0100", {"negative": True, "hh": "01", "mm": "00", "name": "-0100"}),
+            ("+0012", {"negative": False, "hh": "00", "mm": "12", "name": "+0012"}),
+            ("+0123", {"negative": False, "hh": "01", "mm": "23", "name": "+0123"}),
+            ("-0123", {"negative": True, "hh": "01", "mm": "23", "name": "-0123"}),
+            ("+00", {"negative": False, "hh": "00", "mm": None, "name": "+00"}),
+            ("+01", {"negative": False, "hh": "01", "mm": None, "name": "+01"}),
+            ("-01", {"negative": True, "hh": "01", "mm": None, "name": "-01"}),
+            ("+12", {"negative": False, "hh": "12", "mm": None, "name": "+12"}),
+            ("-12", {"negative": True, "hh": "12", "mm": None, "name": "-12"}),
+        )
+
+        for testtuple in testtuples:
+            with mock.patch.object(
+                aniso8601.timezone.PythonTimeBuilder, "build_timezone"
+            ) as mockBuildTimezone:
+
+                mockBuildTimezone.return_value = testtuple[1]
+
+                result = parse_timezone(testtuple[0])
+
+                self.assertEqual(result, testtuple[1])
+                mockBuildTimezone.assert_called_once_with(**testtuple[1])
+
+    def test_parse_timezone_badtype(self):
+        testtuples = (None, 1, False, 1.234)
+
+        for testtuple in testtuples:
+            with self.assertRaises(ValueError):
+                parse_timezone(testtuple, builder=None)
+
+    def test_parse_timezone_badstr(self):
+        testtuples = (
+            "+1",
+            "-00",
+            "-0000",
+            "-00:00",
+            "01",
+            "0123",
+            "@12:34",
+            "Y",
+            " Z",
+            "Z ",
+            " Z ",
+            "bad",
+            "",
+        )
+
+        for testtuple in testtuples:
+            with self.assertRaises(ISOFormatError):
+                parse_timezone(testtuple, builder=None)
+
+    def test_parse_timezone_mockbuilder(self):
+        mockBuilder = mock.Mock()
+
+        expectedargs = {"negative": False, "Z": True, "name": "Z"}
+
+        mockBuilder.build_timezone.return_value = expectedargs
+
+        result = parse_timezone("Z", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_timezone.assert_called_once_with(**expectedargs)
+
+        mockBuilder = mock.Mock()
+
+        expectedargs = {"negative": False, "hh": "00", "mm": "00", "name": "+00:00"}
+
+        mockBuilder.build_timezone.return_value = expectedargs
+
+        result = parse_timezone("+00:00", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_timezone.assert_called_once_with(**expectedargs)
+
+        mockBuilder = mock.Mock()
+
+        expectedargs = {"negative": True, "hh": "01", "mm": "23", "name": "-01:23"}
+
+        mockBuilder.build_timezone.return_value = expectedargs
+
+        result = parse_timezone("-01:23", builder=mockBuilder)
+
+        self.assertEqual(result, expectedargs)
+        mockBuilder.build_timezone.assert_called_once_with(**expectedargs)
+
+    def test_parse_timezone_negativezero(self):
+        # A 0 offset cannot be negative
+        with self.assertRaises(ISOFormatError):
+            parse_timezone("-00:00", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_timezone("-0000", builder=None)
+
+        with self.assertRaises(ISOFormatError):
+            parse_timezone("-00", builder=None)
diff --git a/libs/aniso8601/tests/test_utcoffset.py b/libs/aniso8601/tests/test_utcoffset.py
new file mode 100644
index 000000000..11fa4f7d9
--- /dev/null
+++ b/libs/aniso8601/tests/test_utcoffset.py
@@ -0,0 +1,56 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import datetime
+import pickle
+import unittest
+
+from aniso8601.utcoffset import UTCOffset
+
+
+class TestUTCOffset(unittest.TestCase):
+    def test_pickle(self):
+        # Make sure timezone objects are pickleable
+        testutcoffset = UTCOffset(name="UTC", minutes=0)
+
+        utcoffsetpickle = pickle.dumps(testutcoffset)
+
+        resultutcoffset = pickle.loads(utcoffsetpickle)
+
+        self.assertEqual(resultutcoffset._name, testutcoffset._name)
+        self.assertEqual(resultutcoffset._utcdelta, testutcoffset._utcdelta)
+
+    def test_repr(self):
+        self.assertEqual(str(UTCOffset(minutes=0)), "+0:00:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=60)), "+1:00:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=-60)), "-1:00:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=12)), "+0:12:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=-12)), "-0:12:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=83)), "+1:23:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=-83)), "-1:23:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=1440)), "+1 day, 0:00:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=-1440)), "-1 day, 0:00:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=2967)), "+2 days, 1:27:00 UTC")
+
+        self.assertEqual(str(UTCOffset(minutes=-2967)), "-2 days, 1:27:00 UTC")
+
+    def test_dst(self):
+        tzinfoobject = UTCOffset(minutes=240)
+        # This would raise ISOFormatError or a TypeError if dst info is invalid
+        result = datetime.datetime.now(tzinfoobject)
+        # Hacky way to make sure the tzinfo is what we'd expect
+        self.assertEqual(result.tzinfo.utcoffset(None), datetime.timedelta(hours=4))
diff --git a/libs/aniso8601/time.py b/libs/aniso8601/time.py
new file mode 100644
index 000000000..31fab048e
--- /dev/null
+++ b/libs/aniso8601/time.py
@@ -0,0 +1,203 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+from aniso8601.builders import TupleBuilder
+from aniso8601.builders.python import PythonTimeBuilder
+from aniso8601.compat import is_string
+from aniso8601.date import parse_date
+from aniso8601.decimalfraction import normalize
+from aniso8601.exceptions import ISOFormatError
+from aniso8601.resolution import TimeResolution
+from aniso8601.timezone import parse_timezone
+
+TIMEZONE_DELIMITERS = ["Z", "+", "-"]
+
+
+def get_time_resolution(isotimestr):
+    # Valid time formats are:
+    #
+    # hh:mm:ss
+    # hhmmss
+    # hh:mm
+    # hhmm
+    # hh
+    # hh:mm:ssZ
+    # hhmmssZ
+    # hh:mmZ
+    # hhmmZ
+    # hhZ
+    # hh:mm:ss±hh:mm
+    # hhmmss±hh:mm
+    # hh:mm±hh:mm
+    # hhmm±hh:mm
+    # hh±hh:mm
+    # hh:mm:ss±hhmm
+    # hhmmss±hhmm
+    # hh:mm±hhmm
+    # hhmm±hhmm
+    # hh±hhmm
+    # hh:mm:ss±hh
+    # hhmmss±hh
+    # hh:mm±hh
+    # hhmm±hh
+    # hh±hh
+    isotimetuple = parse_time(isotimestr, builder=TupleBuilder)
+
+    return _get_time_resolution(isotimetuple)
+
+
+def get_datetime_resolution(isodatetimestr, delimiter="T"):
+    # <date>T<time>
+    #
+    # Time part cannot be omittted so return time resolution
+    isotimetuple = parse_datetime(
+        isodatetimestr, delimiter=delimiter, builder=TupleBuilder
+    ).time
+
+    return _get_time_resolution(isotimetuple)
+
+
+def _get_time_resolution(isotimetuple):
+    if isotimetuple.ss is not None:
+        return TimeResolution.Seconds
+
+    if isotimetuple.mm is not None:
+        return TimeResolution.Minutes
+
+    return TimeResolution.Hours
+
+
+def parse_time(isotimestr, builder=PythonTimeBuilder):
+    # Given a string in any ISO 8601 time format, return a datetime.time object
+    # that corresponds to the given time. Fixed offset tzdata will be included
+    # if UTC offset is given in the input string. Valid time formats are:
+    #
+    # hh:mm:ss
+    # hhmmss
+    # hh:mm
+    # hhmm
+    # hh
+    # hh:mm:ssZ
+    # hhmmssZ
+    # hh:mmZ
+    # hhmmZ
+    # hhZ
+    # hh:mm:ss±hh:mm
+    # hhmmss±hh:mm
+    # hh:mm±hh:mm
+    # hhmm±hh:mm
+    # hh±hh:mm
+    # hh:mm:ss±hhmm
+    # hhmmss±hhmm
+    # hh:mm±hhmm
+    # hhmm±hhmm
+    # hh±hhmm
+    # hh:mm:ss±hh
+    # hhmmss±hh
+    # hh:mm±hh
+    # hhmm±hh
+    # hh±hh
+    if is_string(isotimestr) is False:
+        raise ValueError("Time must be string.")
+
+    if len(isotimestr) == 0:
+        raise ISOFormatError('"{0}" is not a valid ISO 8601 time.'.format(isotimestr))
+
+    timestr = normalize(isotimestr)
+
+    hourstr = None
+    minutestr = None
+    secondstr = None
+    tzstr = None
+
+    fractionalstr = None
+
+    # Split out the timezone
+    for delimiter in TIMEZONE_DELIMITERS:
+        delimiteridx = timestr.find(delimiter)
+
+        if delimiteridx != -1:
+            tzstr = timestr[delimiteridx:]
+            timestr = timestr[0:delimiteridx]
+
+    # Split out the fractional component
+    if timestr.find(".") != -1:
+        timestr, fractionalstr = timestr.split(".", 1)
+
+        if fractionalstr.isdigit() is False:
+            raise ISOFormatError(
+                '"{0}" is not a valid ISO 8601 time.'.format(isotimestr)
+            )
+
+    if len(timestr) == 2:
+        # hh
+        hourstr = timestr
+    elif len(timestr) == 4 or len(timestr) == 5:
+        # hh:mm
+        # hhmm
+        if timestr.count(":") == 1:
+            hourstr, minutestr = timestr.split(":")
+        else:
+            hourstr = timestr[0:2]
+            minutestr = timestr[2:]
+    elif len(timestr) == 6 or len(timestr) == 8:
+        # hh:mm:ss
+        # hhmmss
+        if timestr.count(":") == 2:
+            hourstr, minutestr, secondstr = timestr.split(":")
+        else:
+            hourstr = timestr[0:2]
+            minutestr = timestr[2:4]
+            secondstr = timestr[4:]
+    else:
+        raise ISOFormatError('"{0}" is not a valid ISO 8601 time.'.format(isotimestr))
+
+    for componentstr in [hourstr, minutestr, secondstr]:
+        if componentstr is not None and componentstr.isdigit() is False:
+            raise ISOFormatError(
+                '"{0}" is not a valid ISO 8601 time.'.format(isotimestr)
+            )
+
+    if fractionalstr is not None:
+        if secondstr is not None:
+            secondstr = secondstr + "." + fractionalstr
+        elif minutestr is not None:
+            minutestr = minutestr + "." + fractionalstr
+        else:
+            hourstr = hourstr + "." + fractionalstr
+
+    if tzstr is None:
+        tz = None
+    else:
+        tz = parse_timezone(tzstr, builder=TupleBuilder)
+
+    return builder.build_time(hh=hourstr, mm=minutestr, ss=secondstr, tz=tz)
+
+
+def parse_datetime(isodatetimestr, delimiter="T", builder=PythonTimeBuilder):
+    # Given a string in ISO 8601 date time format, return a datetime.datetime
+    # object that corresponds to the given date time.
+    # By default, the ISO 8601 specified T delimiter is used to split the
+    # date and time (<date>T<time>). Fixed offset tzdata will be included
+    # if UTC offset is given in the input string.
+    if is_string(isodatetimestr) is False:
+        raise ValueError("Date time must be string.")
+
+    if delimiter not in isodatetimestr:
+        raise ISOFormatError(
+            'Delimiter "{0}" is not in combined date time '
+            'string "{1}".'.format(delimiter, isodatetimestr)
+        )
+
+    isodatestr, isotimestr = isodatetimestr.split(delimiter, 1)
+
+    datepart = parse_date(isodatestr, builder=TupleBuilder)
+
+    timepart = parse_time(isotimestr, builder=TupleBuilder)
+
+    return builder.build_datetime(datepart, timepart)
diff --git a/libs/aniso8601/timezone.py b/libs/aniso8601/timezone.py
new file mode 100644
index 000000000..3b66105bd
--- /dev/null
+++ b/libs/aniso8601/timezone.py
@@ -0,0 +1,62 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+from aniso8601.builders.python import PythonTimeBuilder
+from aniso8601.compat import is_string
+from aniso8601.exceptions import ISOFormatError
+
+
+def parse_timezone(tzstr, builder=PythonTimeBuilder):
+    # tzstr can be Z, ±hh:mm, ±hhmm, ±hh
+    if is_string(tzstr) is False:
+        raise ValueError("Time zone must be string.")
+
+    if len(tzstr) == 1 and tzstr[0] == "Z":
+        return builder.build_timezone(negative=False, Z=True, name=tzstr)
+    elif len(tzstr) == 6:
+        # ±hh:mm
+        hourstr = tzstr[1:3]
+        minutestr = tzstr[4:6]
+
+        if tzstr[0] == "-" and hourstr == "00" and minutestr == "00":
+            raise ISOFormatError("Negative ISO 8601 time offset must not " "be 0.")
+    elif len(tzstr) == 5:
+        # ±hhmm
+        hourstr = tzstr[1:3]
+        minutestr = tzstr[3:5]
+
+        if tzstr[0] == "-" and hourstr == "00" and minutestr == "00":
+            raise ISOFormatError("Negative ISO 8601 time offset must not " "be 0.")
+    elif len(tzstr) == 3:
+        # ±hh
+        hourstr = tzstr[1:3]
+        minutestr = None
+
+        if tzstr[0] == "-" and hourstr == "00":
+            raise ISOFormatError("Negative ISO 8601 time offset must not " "be 0.")
+    else:
+        raise ISOFormatError('"{0}" is not a valid ISO 8601 time offset.'.format(tzstr))
+
+    for componentstr in [hourstr, minutestr]:
+        if componentstr is not None:
+            if componentstr.isdigit() is False:
+                raise ISOFormatError(
+                    '"{0}" is not a valid ISO 8601 time offset.'.format(tzstr)
+                )
+
+    if tzstr[0] == "+":
+        return builder.build_timezone(
+            negative=False, hh=hourstr, mm=minutestr, name=tzstr
+        )
+
+    if tzstr[0] == "-":
+        return builder.build_timezone(
+            negative=True, hh=hourstr, mm=minutestr, name=tzstr
+        )
+
+    raise ISOFormatError('"{0}" is not a valid ISO 8601 time offset.'.format(tzstr))
diff --git a/libs/aniso8601/utcoffset.py b/libs/aniso8601/utcoffset.py
new file mode 100644
index 000000000..11872a01e
--- /dev/null
+++ b/libs/aniso8601/utcoffset.py
@@ -0,0 +1,71 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2021, Brandon Nielsen
+# All rights reserved.
+#
+# This software may be modified and distributed under the terms
+# of the BSD license.  See the LICENSE file for details.
+
+import datetime
+
+
+class UTCOffset(datetime.tzinfo):
+    def __init__(self, name=None, minutes=None):
+        # We build an offset in this manner since the
+        # tzinfo class must have an init
+        # "method that can be called with no arguments"
+        self._name = name
+
+        if minutes is not None:
+            self._utcdelta = datetime.timedelta(minutes=minutes)
+        else:
+            self._utcdelta = None
+
+    def __repr__(self):
+        if self._utcdelta >= datetime.timedelta(hours=0):
+            return "+{0} UTC".format(self._utcdelta)
+
+        # From the docs:
+        # String representations of timedelta objects are normalized
+        # similarly to their internal representation. This leads to
+        # somewhat unusual results for negative timedeltas.
+
+        # Clean this up for printing purposes
+        # Negative deltas start at -1 day
+        correcteddays = abs(self._utcdelta.days + 1)
+
+        # Negative deltas have a positive seconds
+        deltaseconds = (24 * 60 * 60) - self._utcdelta.seconds
+
+        # (24 hours / day) * (60 minutes / hour) * (60 seconds / hour)
+        days, remainder = divmod(deltaseconds, 24 * 60 * 60)
+
+        # (1 hour) * (60 minutes / hour) * (60 seconds / hour)
+        hours, remainder = divmod(remainder, 1 * 60 * 60)
+
+        # (1 minute) * (60 seconds / minute)
+        minutes, seconds = divmod(remainder, 1 * 60)
+
+        # Add any remaining days to the correcteddays count
+        correcteddays += days
+
+        if correcteddays == 0:
+            return "-{0}:{1:02}:{2:02} UTC".format(hours, minutes, seconds)
+        elif correcteddays == 1:
+            return "-1 day, {0}:{1:02}:{2:02} UTC".format(hours, minutes, seconds)
+
+        return "-{0} days, {1}:{2:02}:{3:02} UTC".format(
+            correcteddays, hours, minutes, seconds
+        )
+
+    def utcoffset(self, dt):
+        return self._utcdelta
+
+    def tzname(self, dt):
+        return self._name
+
+    def dst(self, dt):
+        # ISO 8601 specifies offsets should be different if DST is required,
+        # instead of allowing for a DST to be specified
+        # https://docs.python.org/2/library/datetime.html#datetime.tzinfo.dst
+        return datetime.timedelta(0)