Updated vendored dependencies.

38 files changed, 1399 insertions, 89 deletions

diff --git a/libs/importlib_resources/__init__.py b/libs/importlib_resources/__init__.py
index 15f6b26b9..34e3a9950 100644
--- a/libs/importlib_resources/__init__.py
+++ b/libs/importlib_resources/__init__.py
@@ -17,7 +17,7 @@ from ._legacy import (
     Resource,
 )
 
-from importlib_resources.abc import ResourceReader
+from .abc import ResourceReader
 
 
 __all__ = [
diff --git a/libs/importlib_resources/_common.py b/libs/importlib_resources/_common.py
index a12e2c75d..9f19784d0 100644
--- a/libs/importlib_resources/_common.py
+++ b/libs/importlib_resources/_common.py
@@ -5,25 +5,58 @@ import functools
 import contextlib
 import types
 import importlib
+import inspect
+import warnings
+import itertools
 
-from typing import Union, Optional
+from typing import Union, Optional, cast
 from .abc import ResourceReader, Traversable
 
 from ._compat import wrap_spec
 
 Package = Union[types.ModuleType, str]
+Anchor = Package
 
 
-def files(package):
-    # type: (Package) -> Traversable
+def package_to_anchor(func):
     """
-    Get a Traversable resource from a package
+    Replace 'package' parameter as 'anchor' and warn about the change.
+
+    Other errors should fall through.
+
+    >>> files('a', 'b')
+    Traceback (most recent call last):
+    TypeError: files() takes from 0 to 1 positional arguments but 2 were given
+    """
+    undefined = object()
+
+    @functools.wraps(func)
+    def wrapper(anchor=undefined, package=undefined):
+        if package is not undefined:
+            if anchor is not undefined:
+                return func(anchor, package)
+            warnings.warn(
+                "First parameter to files is renamed to 'anchor'",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            return func(package)
+        elif anchor is undefined:
+            return func()
+        return func(anchor)
+
+    return wrapper
+
+
+@package_to_anchor
+def files(anchor: Optional[Anchor] = None) -> Traversable:
+    """
+    Get a Traversable resource for an anchor.
     """
-    return from_package(get_package(package))
+    return from_package(resolve(anchor))
 
 
-def get_resource_reader(package):
-    # type: (types.ModuleType) -> Optional[ResourceReader]
+def get_resource_reader(package: types.ModuleType) -> Optional[ResourceReader]:
     """
     Return the package's loader if it's a ResourceReader.
     """
@@ -39,24 +72,39 @@ def get_resource_reader(package):
     return reader(spec.name)  # type: ignore
 
 
-def resolve(cand):
-    # type: (Package) -> types.ModuleType
-    return cand if isinstance(cand, types.ModuleType) else importlib.import_module(cand)
[email protected]
+def resolve(cand: Optional[Anchor]) -> types.ModuleType:
+    return cast(types.ModuleType, cand)
+
+
[email protected]
+def _(cand: str) -> types.ModuleType:
+    return importlib.import_module(cand)
+
 
[email protected]
+def _(cand: None) -> types.ModuleType:
+    return resolve(_infer_caller().f_globals['__name__'])
 
-def get_package(package):
-    # type: (Package) -> types.ModuleType
-    """Take a package name or module object and return the module.
 
-    Raise an exception if the resolved module is not a package.
+def _infer_caller():
     """
-    resolved = resolve(package)
-    if wrap_spec(resolved).submodule_search_locations is None:
-        raise TypeError(f'{package!r} is not a package')
-    return resolved
+    Walk the stack and find the frame of the first caller not in this module.
+    """
+
+    def is_this_file(frame_info):
+        return frame_info.filename == __file__
+
+    def is_wrapper(frame_info):
+        return frame_info.function == 'wrapper'
+
+    not_this_file = itertools.filterfalse(is_this_file, inspect.stack())
+    # also exclude 'wrapper' due to singledispatch in the call stack
+    callers = itertools.filterfalse(is_wrapper, not_this_file)
+    return next(callers).frame
 
 
-def from_package(package):
+def from_package(package: types.ModuleType):
     """
     Return a Traversable object for the given package.
 
@@ -67,7 +115,14 @@ def from_package(package):
 
 
 @contextlib.contextmanager
-def _tempfile(reader, suffix=''):
+def _tempfile(
+    reader,
+    suffix='',
+    # gh-93353: Keep a reference to call os.remove() in late Python
+    # finalization.
+    *,
+    _os_remove=os.remove,
+):
     # Not using tempfile.NamedTemporaryFile as it leads to deeper 'try'
     # blocks due to the need to close the temporary file to work on Windows
     # properly.
@@ -81,18 +136,35 @@ def _tempfile(reader, suffix=''):
         yield pathlib.Path(raw_path)
     finally:
         try:
-            os.remove(raw_path)
+            _os_remove(raw_path)
         except FileNotFoundError:
             pass
 
 
+def _temp_file(path):
+    return _tempfile(path.read_bytes, suffix=path.name)
+
+
+def _is_present_dir(path: Traversable) -> bool:
+    """
+    Some Traversables implement ``is_dir()`` to raise an
+    exception (i.e. ``FileNotFoundError``) when the
+    directory doesn't exist. This function wraps that call
+    to always return a boolean and only return True
+    if there's a dir and it exists.
+    """
+    with contextlib.suppress(FileNotFoundError):
+        return path.is_dir()
+    return False
+
+
 @functools.singledispatch
 def as_file(path):
     """
     Given a Traversable object, return that object as a
     path on the local file system in a context manager.
     """
-    return _tempfile(path.read_bytes, suffix=path.name)
+    return _temp_dir(path) if _is_present_dir(path) else _temp_file(path)
 
 
 @as_file.register(pathlib.Path)
@@ -102,3 +174,34 @@ def _(path):
     Degenerate behavior for pathlib.Path objects.
     """
     yield path
+
+
[email protected]
+def _temp_path(dir: tempfile.TemporaryDirectory):
+    """
+    Wrap tempfile.TemporyDirectory to return a pathlib object.
+    """
+    with dir as result:
+        yield pathlib.Path(result)
+
+
[email protected]
+def _temp_dir(path):
+    """
+    Given a traversable dir, recursively replicate the whole tree
+    to the file system in a context manager.
+    """
+    assert path.is_dir()
+    with _temp_path(tempfile.TemporaryDirectory()) as temp_dir:
+        yield _write_contents(temp_dir, path)
+
+
+def _write_contents(target, source):
+    child = target.joinpath(source.name)
+    if source.is_dir():
+        child.mkdir()
+        for item in source.iterdir():
+            _write_contents(child, item)
+    else:
+        child.open('wb').write(source.read_bytes())
+    return child
diff --git a/libs/importlib_resources/_compat.py b/libs/importlib_resources/_compat.py
index 61e48d47d..8d7ade08c 100644
--- a/libs/importlib_resources/_compat.py
+++ b/libs/importlib_resources/_compat.py
@@ -1,9 +1,12 @@
 # flake8: noqa
 
 import abc
+import os
 import sys
 import pathlib
 from contextlib import suppress
+from typing import Union
+
 
 if sys.version_info >= (3, 10):
     from zipfile import Path as ZipPath  # type: ignore
@@ -96,3 +99,10 @@ def wrap_spec(package):
     from . import _adapters
 
     return _adapters.SpecLoaderAdapter(package.__spec__, TraversableResourcesLoader)
+
+
+if sys.version_info >= (3, 9):
+    StrPath = Union[str, os.PathLike[str]]
+else:
+    # PathLike is only subscriptable at runtime in 3.9+
+    StrPath = Union[str, "os.PathLike[str]"]
diff --git a/libs/importlib_resources/_legacy.py b/libs/importlib_resources/_legacy.py
index 1d5d3f1fb..b1ea8105d 100644
--- a/libs/importlib_resources/_legacy.py
+++ b/libs/importlib_resources/_legacy.py
@@ -27,8 +27,7 @@ def deprecated(func):
     return wrapper
 
 
-def normalize_path(path):
-    # type: (Any) -> str
+def normalize_path(path: Any) -> str:
     """Normalize a path by ensuring it is a string.
 
     If the resulting string contains path separators, an exception is raised.
diff --git a/libs/importlib_resources/abc.py b/libs/importlib_resources/abc.py
index d39dc1adb..23b6aeafe 100644
--- a/libs/importlib_resources/abc.py
+++ b/libs/importlib_resources/abc.py
@@ -1,7 +1,13 @@
 import abc
-from typing import BinaryIO, Iterable, Text
+import io
+import itertools
+import pathlib
+from typing import Any, BinaryIO, Iterable, Iterator, NoReturn, Text, Optional
 
-from ._compat import runtime_checkable, Protocol
+from ._compat import runtime_checkable, Protocol, StrPath
+
+
+__all__ = ["ResourceReader", "Traversable", "TraversableResources"]
 
 
 class ResourceReader(metaclass=abc.ABCMeta):
@@ -46,27 +52,34 @@ class ResourceReader(metaclass=abc.ABCMeta):
         raise FileNotFoundError
 
 
+class TraversalError(Exception):
+    pass
+
+
 @runtime_checkable
 class Traversable(Protocol):
     """
     An object with a subset of pathlib.Path methods suitable for
     traversing directories and opening files.
+
+    Any exceptions that occur when accessing the backing resource
+    may propagate unaltered.
     """
 
     @abc.abstractmethod
-    def iterdir(self):
+    def iterdir(self) -> Iterator["Traversable"]:
         """
         Yield Traversable objects in self
         """
 
-    def read_bytes(self):
+    def read_bytes(self) -> bytes:
         """
         Read contents of self as bytes
         """
         with self.open('rb') as strm:
             return strm.read()
 
-    def read_text(self, encoding=None):
+    def read_text(self, encoding: Optional[str] = None) -> str:
         """
         Read contents of self as text
         """
@@ -85,13 +98,32 @@ class Traversable(Protocol):
         Return True if self is a file
         """
 
-    @abc.abstractmethod
-    def joinpath(self, child):
+    def joinpath(self, *descendants: StrPath) -> "Traversable":
         """
-        Return Traversable child in self
+        Return Traversable resolved with any descendants applied.
+
+        Each descendant should be a path segment relative to self
+        and each may contain multiple levels separated by
+        ``posixpath.sep`` (``/``).
         """
+        if not descendants:
+            return self
+        names = itertools.chain.from_iterable(
+            path.parts for path in map(pathlib.PurePosixPath, descendants)
+        )
+        target = next(names)
+        matches = (
+            traversable for traversable in self.iterdir() if traversable.name == target
+        )
+        try:
+            match = next(matches)
+        except StopIteration:
+            raise TraversalError(
+                "Target not found during traversal.", target, list(names)
+            )
+        return match.joinpath(*names)
 
-    def __truediv__(self, child):
+    def __truediv__(self, child: StrPath) -> "Traversable":
         """
         Return Traversable child in self
         """
@@ -107,7 +139,8 @@ class Traversable(Protocol):
         accepted by io.TextIOWrapper.
         """
 
-    @abc.abstractproperty
+    @property
+    @abc.abstractmethod
     def name(self) -> str:
         """
         The base name of this object without any parent references.
@@ -121,17 +154,17 @@ class TraversableResources(ResourceReader):
     """
 
     @abc.abstractmethod
-    def files(self):
+    def files(self) -> "Traversable":
         """Return a Traversable object for the loaded package."""
 
-    def open_resource(self, resource):
+    def open_resource(self, resource: StrPath) -> io.BufferedReader:
         return self.files().joinpath(resource).open('rb')
 
-    def resource_path(self, resource):
+    def resource_path(self, resource: Any) -> NoReturn:
         raise FileNotFoundError(resource)
 
-    def is_resource(self, path):
+    def is_resource(self, path: StrPath) -> bool:
         return self.files().joinpath(path).is_file()
 
-    def contents(self):
+    def contents(self) -> Iterator[str]:
         return (item.name for item in self.files().iterdir())
diff --git a/libs/importlib_resources/readers.py b/libs/importlib_resources/readers.py
index f1190ca45..ab34db740 100644
--- a/libs/importlib_resources/readers.py
+++ b/libs/importlib_resources/readers.py
@@ -82,15 +82,13 @@ class MultiplexedPath(abc.Traversable):
     def is_file(self):
         return False
 
-    def joinpath(self, child):
-        # first try to find child in current paths
-        for file in self.iterdir():
-            if file.name == child:
-                return file
-        # if it does not exist, construct it with the first path
-        return self._paths[0] / child
-
-    __truediv__ = joinpath
+    def joinpath(self, *descendants):
+        try:
+            return super().joinpath(*descendants)
+        except abc.TraversalError:
+            # One of the paths did not resolve (a directory does not exist).
+            # Just return something that will not exist.
+            return self._paths[0].joinpath(*descendants)
 
     def open(self, *args, **kwargs):
         raise FileNotFoundError(f'{self} is not a file')
diff --git a/libs/importlib_resources/simple.py b/libs/importlib_resources/simple.py
index da073cbdb..7770c922c 100644
--- a/libs/importlib_resources/simple.py
+++ b/libs/importlib_resources/simple.py
@@ -16,31 +16,28 @@ class SimpleReader(abc.ABC):
     provider.
     """
 
-    @abc.abstractproperty
-    def package(self):
-        # type: () -> str
+    @property
+    @abc.abstractmethod
+    def package(self) -> str:
         """
         The name of the package for which this reader loads resources.
         """
 
     @abc.abstractmethod
-    def children(self):
-        # type: () -> List['SimpleReader']
+    def children(self) -> List['SimpleReader']:
         """
         Obtain an iterable of SimpleReader for available
         child containers (e.g. directories).
         """
 
     @abc.abstractmethod
-    def resources(self):
-        # type: () -> List[str]
+    def resources(self) -> List[str]:
         """
         Obtain available named resources for this virtual package.
         """
 
     @abc.abstractmethod
-    def open_binary(self, resource):
-        # type: (str) -> BinaryIO
+    def open_binary(self, resource: str) -> BinaryIO:
         """
         Obtain a File-like for a named resource.
         """
@@ -50,39 +47,12 @@ class SimpleReader(abc.ABC):
         return self.package.split('.')[-1]
 
 
-class ResourceHandle(Traversable):
-    """
-    Handle to a named resource in a ResourceReader.
-    """
-
-    def __init__(self, parent, name):
-        # type: (ResourceContainer, str) -> None
-        self.parent = parent
-        self.name = name  # type: ignore
-
-    def is_file(self):
-        return True
-
-    def is_dir(self):
-        return False
-
-    def open(self, mode='r', *args, **kwargs):
-        stream = self.parent.reader.open_binary(self.name)
-        if 'b' not in mode:
-            stream = io.TextIOWrapper(*args, **kwargs)
-        return stream
-
-    def joinpath(self, name):
-        raise RuntimeError("Cannot traverse into a resource")
-
-
 class ResourceContainer(Traversable):
     """
     Traversable container for a package's resources via its reader.
     """
 
-    def __init__(self, reader):
-        # type: (SimpleReader) -> None
+    def __init__(self, reader: SimpleReader):
         self.reader = reader
 
     def is_dir(self):
@@ -99,10 +69,30 @@ class ResourceContainer(Traversable):
     def open(self, *args, **kwargs):
         raise IsADirectoryError()
 
+
+class ResourceHandle(Traversable):
+    """
+    Handle to a named resource in a ResourceReader.
+    """
+
+    def __init__(self, parent: ResourceContainer, name: str):
+        self.parent = parent
+        self.name = name  # type: ignore
+
+    def is_file(self):
+        return True
+
+    def is_dir(self):
+        return False
+
+    def open(self, mode='r', *args, **kwargs):
+        stream = self.parent.reader.open_binary(self.name)
+        if 'b' not in mode:
+            stream = io.TextIOWrapper(*args, **kwargs)
+        return stream
+
     def joinpath(self, name):
-        return next(
-            traversable for traversable in self.iterdir() if traversable.name == name
-        )
+        raise RuntimeError("Cannot traverse into a resource")
 
 
 class TraversableReader(TraversableResources, SimpleReader):
diff --git a/libs/importlib_resources/tests/__init__.py b/libs/importlib_resources/tests/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libs/importlib_resources/tests/__init__.py
diff --git a/libs/importlib_resources/tests/_compat.py b/libs/importlib_resources/tests/_compat.py
new file mode 100644
index 000000000..e7bf06dd4
--- /dev/null
+++ b/libs/importlib_resources/tests/_compat.py
@@ -0,0 +1,32 @@
+import os
+
+
+try:
+    from test.support import import_helper  # type: ignore
+except ImportError:
+    # Python 3.9 and earlier
+    class import_helper:  # type: ignore
+        from test.support import (
+            modules_setup,
+            modules_cleanup,
+            DirsOnSysPath,
+            CleanImport,
+        )
+
+
+try:
+    from test.support import os_helper  # type: ignore
+except ImportError:
+    # Python 3.9 compat
+    class os_helper:  # type:ignore
+        from test.support import temp_dir
+
+
+try:
+    # Python 3.10
+    from test.support.os_helper import unlink
+except ImportError:
+    from test.support import unlink as _unlink
+
+    def unlink(target):
+        return _unlink(os.fspath(target))
diff --git a/libs/importlib_resources/tests/_path.py b/libs/importlib_resources/tests/_path.py
new file mode 100644
index 000000000..c630e4d3d
--- /dev/null
+++ b/libs/importlib_resources/tests/_path.py
@@ -0,0 +1,50 @@
+import pathlib
+import functools
+
+
+####
+# from jaraco.path 3.4
+
+
+def build(spec, prefix=pathlib.Path()):
+    """
+    Build a set of files/directories, as described by the spec.
+
+    Each key represents a pathname, and the value represents
+    the content. Content may be a nested directory.
+
+    >>> spec = {
+    ...     'README.txt': "A README file",
+    ...     "foo": {
+    ...         "__init__.py": "",
+    ...         "bar": {
+    ...             "__init__.py": "",
+    ...         },
+    ...         "baz.py": "# Some code",
+    ...     }
+    ... }
+    >>> tmpdir = getfixture('tmpdir')
+    >>> build(spec, tmpdir)
+    """
+    for name, contents in spec.items():
+        create(contents, pathlib.Path(prefix) / name)
+
+
[email protected]
+def create(content, path):
+    path.mkdir(exist_ok=True)
+    build(content, prefix=path)  # type: ignore
+
+
[email protected]
+def _(content: bytes, path):
+    path.write_bytes(content)
+
+
[email protected]
+def _(content: str, path):
+    path.write_text(content)
+
+
+# end from jaraco.path
+####
diff --git a/libs/importlib_resources/tests/data01/__init__.py b/libs/importlib_resources/tests/data01/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libs/importlib_resources/tests/data01/__init__.py
diff --git a/libs/importlib_resources/tests/data01/binary.file b/libs/importlib_resources/tests/data01/binary.file
new file mode 100644
index 000000000..eaf36c1da
--- /dev/null
+++ b/libs/importlib_resources/tests/data01/binary.file
diff --git a/libs/importlib_resources/tests/data01/subdirectory/__init__.py b/libs/importlib_resources/tests/data01/subdirectory/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libs/importlib_resources/tests/data01/subdirectory/__init__.py
diff --git a/libs/importlib_resources/tests/data01/subdirectory/binary.file b/libs/importlib_resources/tests/data01/subdirectory/binary.file
new file mode 100644
index 000000000..eaf36c1da
--- /dev/null
+++ b/libs/importlib_resources/tests/data01/subdirectory/binary.file
diff --git a/libs/importlib_resources/tests/data01/utf-16.file b/libs/importlib_resources/tests/data01/utf-16.file
new file mode 100644
index 000000000..2cb772295
--- /dev/null
+++ b/libs/importlib_resources/tests/data01/utf-16.file
diff --git a/libs/importlib_resources/tests/data01/utf-8.file b/libs/importlib_resources/tests/data01/utf-8.file
new file mode 100644
index 000000000..1c0132ad9
--- /dev/null
+++ b/libs/importlib_resources/tests/data01/utf-8.file
@@ -0,0 +1 @@
+Hello, UTF-8 world!
diff --git a/libs/importlib_resources/tests/data02/__init__.py b/libs/importlib_resources/tests/data02/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libs/importlib_resources/tests/data02/__init__.py
diff --git a/libs/importlib_resources/tests/data02/one/__init__.py b/libs/importlib_resources/tests/data02/one/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libs/importlib_resources/tests/data02/one/__init__.py
diff --git a/libs/importlib_resources/tests/data02/one/resource1.txt b/libs/importlib_resources/tests/data02/one/resource1.txt
new file mode 100644
index 000000000..61a813e40
--- /dev/null
+++ b/libs/importlib_resources/tests/data02/one/resource1.txt
@@ -0,0 +1 @@
+one resource
diff --git a/libs/importlib_resources/tests/data02/two/__init__.py b/libs/importlib_resources/tests/data02/two/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libs/importlib_resources/tests/data02/two/__init__.py
diff --git a/libs/importlib_resources/tests/data02/two/resource2.txt b/libs/importlib_resources/tests/data02/two/resource2.txt
new file mode 100644
index 000000000..a80ce46ea
--- /dev/null
+++ b/libs/importlib_resources/tests/data02/two/resource2.txt
@@ -0,0 +1 @@
+two resource
diff --git a/libs/importlib_resources/tests/namespacedata01/binary.file b/libs/importlib_resources/tests/namespacedata01/binary.file
new file mode 100644
index 000000000..eaf36c1da
--- /dev/null
+++ b/libs/importlib_resources/tests/namespacedata01/binary.file
diff --git a/libs/importlib_resources/tests/namespacedata01/utf-16.file b/libs/importlib_resources/tests/namespacedata01/utf-16.file
new file mode 100644
index 000000000..2cb772295
--- /dev/null
+++ b/libs/importlib_resources/tests/namespacedata01/utf-16.file
diff --git a/libs/importlib_resources/tests/namespacedata01/utf-8.file b/libs/importlib_resources/tests/namespacedata01/utf-8.file
new file mode 100644
index 000000000..1c0132ad9
--- /dev/null
+++ b/libs/importlib_resources/tests/namespacedata01/utf-8.file
@@ -0,0 +1 @@
+Hello, UTF-8 world!
diff --git a/libs/importlib_resources/tests/test_compatibilty_files.py b/libs/importlib_resources/tests/test_compatibilty_files.py
new file mode 100644
index 000000000..d92c7c56c
--- /dev/null
+++ b/libs/importlib_resources/tests/test_compatibilty_files.py
@@ -0,0 +1,102 @@
+import io
+import unittest
+
+import importlib_resources as resources
+
+from importlib_resources._adapters import (
+    CompatibilityFiles,
+    wrap_spec,
+)
+
+from . import util
+
+
+class CompatibilityFilesTests(unittest.TestCase):
+    @property
+    def package(self):
+        bytes_data = io.BytesIO(b'Hello, world!')
+        return util.create_package(
+            file=bytes_data,
+            path='some_path',
+            contents=('a', 'b', 'c'),
+        )
+
+    @property
+    def files(self):
+        return resources.files(self.package)
+
+    def test_spec_path_iter(self):
+        self.assertEqual(
+            sorted(path.name for path in self.files.iterdir()),
+            ['a', 'b', 'c'],
+        )
+
+    def test_child_path_iter(self):
+        self.assertEqual(list((self.files / 'a').iterdir()), [])
+
+    def test_orphan_path_iter(self):
+        self.assertEqual(list((self.files / 'a' / 'a').iterdir()), [])
+        self.assertEqual(list((self.files / 'a' / 'a' / 'a').iterdir()), [])
+
+    def test_spec_path_is(self):
+        self.assertFalse(self.files.is_file())
+        self.assertFalse(self.files.is_dir())
+
+    def test_child_path_is(self):
+        self.assertTrue((self.files / 'a').is_file())
+        self.assertFalse((self.files / 'a').is_dir())
+
+    def test_orphan_path_is(self):
+        self.assertFalse((self.files / 'a' / 'a').is_file())
+        self.assertFalse((self.files / 'a' / 'a').is_dir())
+        self.assertFalse((self.files / 'a' / 'a' / 'a').is_file())
+        self.assertFalse((self.files / 'a' / 'a' / 'a').is_dir())
+
+    def test_spec_path_name(self):
+        self.assertEqual(self.files.name, 'testingpackage')
+
+    def test_child_path_name(self):
+        self.assertEqual((self.files / 'a').name, 'a')
+
+    def test_orphan_path_name(self):
+        self.assertEqual((self.files / 'a' / 'b').name, 'b')
+        self.assertEqual((self.files / 'a' / 'b' / 'c').name, 'c')
+
+    def test_spec_path_open(self):
+        self.assertEqual(self.files.read_bytes(), b'Hello, world!')
+        self.assertEqual(self.files.read_text(), 'Hello, world!')
+
+    def test_child_path_open(self):
+        self.assertEqual((self.files / 'a').read_bytes(), b'Hello, world!')
+        self.assertEqual((self.files / 'a').read_text(), 'Hello, world!')
+
+    def test_orphan_path_open(self):
+        with self.assertRaises(FileNotFoundError):
+            (self.files / 'a' / 'b').read_bytes()
+        with self.assertRaises(FileNotFoundError):
+            (self.files / 'a' / 'b' / 'c').read_bytes()
+
+    def test_open_invalid_mode(self):
+        with self.assertRaises(ValueError):
+            self.files.open('0')
+
+    def test_orphan_path_invalid(self):
+        with self.assertRaises(ValueError):
+            CompatibilityFiles.OrphanPath()
+
+    def test_wrap_spec(self):
+        spec = wrap_spec(self.package)
+        self.assertIsInstance(spec.loader.get_resource_reader(None), CompatibilityFiles)
+
+
+class CompatibilityFilesNoReaderTests(unittest.TestCase):
+    @property
+    def package(self):
+        return util.create_package_from_loader(None)
+
+    @property
+    def files(self):
+        return resources.files(self.package)
+
+    def test_spec_path_joinpath(self):
+        self.assertIsInstance(self.files / 'a', CompatibilityFiles.OrphanPath)
diff --git a/libs/importlib_resources/tests/test_contents.py b/libs/importlib_resources/tests/test_contents.py
new file mode 100644
index 000000000..525568e8c
--- /dev/null
+++ b/libs/importlib_resources/tests/test_contents.py
@@ -0,0 +1,43 @@
+import unittest
+import importlib_resources as resources
+
+from . import data01
+from . import util
+
+
+class ContentsTests:
+    expected = {
+        '__init__.py',
+        'binary.file',
+        'subdirectory',
+        'utf-16.file',
+        'utf-8.file',
+    }
+
+    def test_contents(self):
+        contents = {path.name for path in resources.files(self.data).iterdir()}
+        assert self.expected <= contents
+
+
+class ContentsDiskTests(ContentsTests, unittest.TestCase):
+    def setUp(self):
+        self.data = data01
+
+
+class ContentsZipTests(ContentsTests, util.ZipSetup, unittest.TestCase):
+    pass
+
+
+class ContentsNamespaceTests(ContentsTests, unittest.TestCase):
+    expected = {
+        # no __init__ because of namespace design
+        # no subdirectory as incidental difference in fixture
+        'binary.file',
+        'utf-16.file',
+        'utf-8.file',
+    }
+
+    def setUp(self):
+        from . import namespacedata01
+
+        self.data = namespacedata01
diff --git a/libs/importlib_resources/tests/test_files.py b/libs/importlib_resources/tests/test_files.py
new file mode 100644
index 000000000..d258fb5f0
--- /dev/null
+++ b/libs/importlib_resources/tests/test_files.py
@@ -0,0 +1,112 @@
+import typing
+import textwrap
+import unittest
+import warnings
+import importlib
+import contextlib
+
+import importlib_resources as resources
+from ..abc import Traversable
+from . import data01
+from . import util
+from . import _path
+from ._compat import os_helper, import_helper
+
+
[email protected]
+def suppress_known_deprecation():
+    with warnings.catch_warnings(record=True) as ctx:
+        warnings.simplefilter('default', category=DeprecationWarning)
+        yield ctx
+
+
+class FilesTests:
+    def test_read_bytes(self):
+        files = resources.files(self.data)
+        actual = files.joinpath('utf-8.file').read_bytes()
+        assert actual == b'Hello, UTF-8 world!\n'
+
+    def test_read_text(self):
+        files = resources.files(self.data)
+        actual = files.joinpath('utf-8.file').read_text(encoding='utf-8')
+        assert actual == 'Hello, UTF-8 world!\n'
+
+    @unittest.skipUnless(
+        hasattr(typing, 'runtime_checkable'),
+        "Only suitable when typing supports runtime_checkable",
+    )
+    def test_traversable(self):
+        assert isinstance(resources.files(self.data), Traversable)
+
+    def test_old_parameter(self):
+        """
+        Files used to take a 'package' parameter. Make sure anyone
+        passing by name is still supported.
+        """
+        with suppress_known_deprecation():
+            resources.files(package=self.data)
+
+
+class OpenDiskTests(FilesTests, unittest.TestCase):
+    def setUp(self):
+        self.data = data01
+
+
+class OpenZipTests(FilesTests, util.ZipSetup, unittest.TestCase):
+    pass
+
+
+class OpenNamespaceTests(FilesTests, unittest.TestCase):
+    def setUp(self):
+        from . import namespacedata01
+
+        self.data = namespacedata01
+
+
+class SiteDir:
+    def setUp(self):
+        self.fixtures = contextlib.ExitStack()
+        self.addCleanup(self.fixtures.close)
+        self.site_dir = self.fixtures.enter_context(os_helper.temp_dir())
+        self.fixtures.enter_context(import_helper.DirsOnSysPath(self.site_dir))
+        self.fixtures.enter_context(import_helper.CleanImport())
+
+
+class ModulesFilesTests(SiteDir, unittest.TestCase):
+    def test_module_resources(self):
+        """
+        A module can have resources found adjacent to the module.
+        """
+        spec = {
+            'mod.py': '',
+            'res.txt': 'resources are the best',
+        }
+        _path.build(spec, self.site_dir)
+        import mod
+
+        actual = resources.files(mod).joinpath('res.txt').read_text()
+        assert actual == spec['res.txt']
+
+
+class ImplicitContextFilesTests(SiteDir, unittest.TestCase):
+    def test_implicit_files(self):
+        """
+        Without any parameter, files() will infer the location as the caller.
+        """
+        spec = {
+            'somepkg': {
+                '__init__.py': textwrap.dedent(
+                    """
+                    import importlib_resources as res
+                    val = res.files().joinpath('res.txt').read_text()
+                    """
+                ),
+                'res.txt': 'resources are the best',
+            },
+        }
+        _path.build(spec, self.site_dir)
+        assert importlib.import_module('somepkg').val == 'resources are the best'
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/libs/importlib_resources/tests/test_open.py b/libs/importlib_resources/tests/test_open.py
new file mode 100644
index 000000000..87b42c3d3
--- /dev/null
+++ b/libs/importlib_resources/tests/test_open.py
@@ -0,0 +1,81 @@
+import unittest
+
+import importlib_resources as resources
+from . import data01
+from . import util
+
+
+class CommonBinaryTests(util.CommonTests, unittest.TestCase):
+    def execute(self, package, path):
+        target = resources.files(package).joinpath(path)
+        with target.open('rb'):
+            pass
+
+
+class CommonTextTests(util.CommonTests, unittest.TestCase):
+    def execute(self, package, path):
+        target = resources.files(package).joinpath(path)
+        with target.open():
+            pass
+
+
+class OpenTests:
+    def test_open_binary(self):
+        target = resources.files(self.data) / 'binary.file'
+        with target.open('rb') as fp:
+            result = fp.read()
+            self.assertEqual(result, b'\x00\x01\x02\x03')
+
+    def test_open_text_default_encoding(self):
+        target = resources.files(self.data) / 'utf-8.file'
+        with target.open() as fp:
+            result = fp.read()
+            self.assertEqual(result, 'Hello, UTF-8 world!\n')
+
+    def test_open_text_given_encoding(self):
+        target = resources.files(self.data) / 'utf-16.file'
+        with target.open(encoding='utf-16', errors='strict') as fp:
+            result = fp.read()
+        self.assertEqual(result, 'Hello, UTF-16 world!\n')
+
+    def test_open_text_with_errors(self):
+        # Raises UnicodeError without the 'errors' argument.
+        target = resources.files(self.data) / 'utf-16.file'
+        with target.open(encoding='utf-8', errors='strict') as fp:
+            self.assertRaises(UnicodeError, fp.read)
+        with target.open(encoding='utf-8', errors='ignore') as fp:
+            result = fp.read()
+        self.assertEqual(
+            result,
+            'H\x00e\x00l\x00l\x00o\x00,\x00 '
+            '\x00U\x00T\x00F\x00-\x001\x006\x00 '
+            '\x00w\x00o\x00r\x00l\x00d\x00!\x00\n\x00',
+        )
+
+    def test_open_binary_FileNotFoundError(self):
+        target = resources.files(self.data) / 'does-not-exist'
+        self.assertRaises(FileNotFoundError, target.open, 'rb')
+
+    def test_open_text_FileNotFoundError(self):
+        target = resources.files(self.data) / 'does-not-exist'
+        self.assertRaises(FileNotFoundError, target.open)
+
+
+class OpenDiskTests(OpenTests, unittest.TestCase):
+    def setUp(self):
+        self.data = data01
+
+
+class OpenDiskNamespaceTests(OpenTests, unittest.TestCase):
+    def setUp(self):
+        from . import namespacedata01
+
+        self.data = namespacedata01
+
+
+class OpenZipTests(OpenTests, util.ZipSetup, unittest.TestCase):
+    pass
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/libs/importlib_resources/tests/test_path.py b/libs/importlib_resources/tests/test_path.py
new file mode 100644
index 000000000..4f4d3943b
--- /dev/null
+++ b/libs/importlib_resources/tests/test_path.py
@@ -0,0 +1,64 @@
+import io
+import unittest
+
+import importlib_resources as resources
+from . import data01
+from . import util
+
+
+class CommonTests(util.CommonTests, unittest.TestCase):
+    def execute(self, package, path):
+        with resources.as_file(resources.files(package).joinpath(path)):
+            pass
+
+
+class PathTests:
+    def test_reading(self):
+        # Path should be readable.
+        # Test also implicitly verifies the returned object is a pathlib.Path
+        # instance.
+        target = resources.files(self.data) / 'utf-8.file'
+        with resources.as_file(target) as path:
+            self.assertTrue(path.name.endswith("utf-8.file"), repr(path))
+            # pathlib.Path.read_text() was introduced in Python 3.5.
+            with path.open('r', encoding='utf-8') as file:
+                text = file.read()
+            self.assertEqual('Hello, UTF-8 world!\n', text)
+
+
+class PathDiskTests(PathTests, unittest.TestCase):
+    data = data01
+
+    def test_natural_path(self):
+        """
+        Guarantee the internal implementation detail that
+        file-system-backed resources do not get the tempdir
+        treatment.
+        """
+        target = resources.files(self.data) / 'utf-8.file'
+        with resources.as_file(target) as path:
+            assert 'data' in str(path)
+
+
+class PathMemoryTests(PathTests, unittest.TestCase):
+    def setUp(self):
+        file = io.BytesIO(b'Hello, UTF-8 world!\n')
+        self.addCleanup(file.close)
+        self.data = util.create_package(
+            file=file, path=FileNotFoundError("package exists only in memory")
+        )
+        self.data.__spec__.origin = None
+        self.data.__spec__.has_location = False
+
+
+class PathZipTests(PathTests, util.ZipSetup, unittest.TestCase):
+    def test_remove_in_context_manager(self):
+        # It is not an error if the file that was temporarily stashed on the
+        # file system is removed inside the `with` stanza.
+        target = resources.files(self.data) / 'utf-8.file'
+        with resources.as_file(target) as path:
+            path.unlink()
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/libs/importlib_resources/tests/test_read.py b/libs/importlib_resources/tests/test_read.py
new file mode 100644
index 000000000..41dd6db5f
--- /dev/null
+++ b/libs/importlib_resources/tests/test_read.py
@@ -0,0 +1,76 @@
+import unittest
+import importlib_resources as resources
+
+from . import data01
+from . import util
+from importlib import import_module
+
+
+class CommonBinaryTests(util.CommonTests, unittest.TestCase):
+    def execute(self, package, path):
+        resources.files(package).joinpath(path).read_bytes()
+
+
+class CommonTextTests(util.CommonTests, unittest.TestCase):
+    def execute(self, package, path):
+        resources.files(package).joinpath(path).read_text()
+
+
+class ReadTests:
+    def test_read_bytes(self):
+        result = resources.files(self.data).joinpath('binary.file').read_bytes()
+        self.assertEqual(result, b'\0\1\2\3')
+
+    def test_read_text_default_encoding(self):
+        result = resources.files(self.data).joinpath('utf-8.file').read_text()
+        self.assertEqual(result, 'Hello, UTF-8 world!\n')
+
+    def test_read_text_given_encoding(self):
+        result = (
+            resources.files(self.data)
+            .joinpath('utf-16.file')
+            .read_text(encoding='utf-16')
+        )
+        self.assertEqual(result, 'Hello, UTF-16 world!\n')
+
+    def test_read_text_with_errors(self):
+        # Raises UnicodeError without the 'errors' argument.
+        target = resources.files(self.data) / 'utf-16.file'
+        self.assertRaises(UnicodeError, target.read_text, encoding='utf-8')
+        result = target.read_text(encoding='utf-8', errors='ignore')
+        self.assertEqual(
+            result,
+            'H\x00e\x00l\x00l\x00o\x00,\x00 '
+            '\x00U\x00T\x00F\x00-\x001\x006\x00 '
+            '\x00w\x00o\x00r\x00l\x00d\x00!\x00\n\x00',
+        )
+
+
+class ReadDiskTests(ReadTests, unittest.TestCase):
+    data = data01
+
+
+class ReadZipTests(ReadTests, util.ZipSetup, unittest.TestCase):
+    def test_read_submodule_resource(self):
+        submodule = import_module('ziptestdata.subdirectory')
+        result = resources.files(submodule).joinpath('binary.file').read_bytes()
+        self.assertEqual(result, b'\0\1\2\3')
+
+    def test_read_submodule_resource_by_name(self):
+        result = (
+            resources.files('ziptestdata.subdirectory')
+            .joinpath('binary.file')
+            .read_bytes()
+        )
+        self.assertEqual(result, b'\0\1\2\3')
+
+
+class ReadNamespaceTests(ReadTests, unittest.TestCase):
+    def setUp(self):
+        from . import namespacedata01
+
+        self.data = namespacedata01
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/libs/importlib_resources/tests/test_reader.py b/libs/importlib_resources/tests/test_reader.py
new file mode 100644
index 000000000..1c8ebeeb1
--- /dev/null
+++ b/libs/importlib_resources/tests/test_reader.py
@@ -0,0 +1,133 @@
+import os.path
+import sys
+import pathlib
+import unittest
+
+from importlib import import_module
+from importlib_resources.readers import MultiplexedPath, NamespaceReader
+
+
+class MultiplexedPathTest(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        path = pathlib.Path(__file__).parent / 'namespacedata01'
+        cls.folder = str(path)
+
+    def test_init_no_paths(self):
+        with self.assertRaises(FileNotFoundError):
+            MultiplexedPath()
+
+    def test_init_file(self):
+        with self.assertRaises(NotADirectoryError):
+            MultiplexedPath(os.path.join(self.folder, 'binary.file'))
+
+    def test_iterdir(self):
+        contents = {path.name for path in MultiplexedPath(self.folder).iterdir()}
+        try:
+            contents.remove('__pycache__')
+        except (KeyError, ValueError):
+            pass
+        self.assertEqual(contents, {'binary.file', 'utf-16.file', 'utf-8.file'})
+
+    def test_iterdir_duplicate(self):
+        data01 = os.path.abspath(os.path.join(__file__, '..', 'data01'))
+        contents = {
+            path.name for path in MultiplexedPath(self.folder, data01).iterdir()
+        }
+        for remove in ('__pycache__', '__init__.pyc'):
+            try:
+                contents.remove(remove)
+            except (KeyError, ValueError):
+                pass
+        self.assertEqual(
+            contents,
+            {'__init__.py', 'binary.file', 'subdirectory', 'utf-16.file', 'utf-8.file'},
+        )
+
+    def test_is_dir(self):
+        self.assertEqual(MultiplexedPath(self.folder).is_dir(), True)
+
+    def test_is_file(self):
+        self.assertEqual(MultiplexedPath(self.folder).is_file(), False)
+
+    def test_open_file(self):
+        path = MultiplexedPath(self.folder)
+        with self.assertRaises(FileNotFoundError):
+            path.read_bytes()
+        with self.assertRaises(FileNotFoundError):
+            path.read_text()
+        with self.assertRaises(FileNotFoundError):
+            path.open()
+
+    def test_join_path(self):
+        prefix = os.path.abspath(os.path.join(__file__, '..'))
+        data01 = os.path.join(prefix, 'data01')
+        path = MultiplexedPath(self.folder, data01)
+        self.assertEqual(
+            str(path.joinpath('binary.file'))[len(prefix) + 1 :],
+            os.path.join('namespacedata01', 'binary.file'),
+        )
+        self.assertEqual(
+            str(path.joinpath('subdirectory'))[len(prefix) + 1 :],
+            os.path.join('data01', 'subdirectory'),
+        )
+        self.assertEqual(
+            str(path.joinpath('imaginary'))[len(prefix) + 1 :],
+            os.path.join('namespacedata01', 'imaginary'),
+        )
+        self.assertEqual(path.joinpath(), path)
+
+    def test_join_path_compound(self):
+        path = MultiplexedPath(self.folder)
+        assert not path.joinpath('imaginary/foo.py').exists()
+
+    def test_repr(self):
+        self.assertEqual(
+            repr(MultiplexedPath(self.folder)),
+            f"MultiplexedPath('{self.folder}')",
+        )
+
+    def test_name(self):
+        self.assertEqual(
+            MultiplexedPath(self.folder).name,
+            os.path.basename(self.folder),
+        )
+
+
+class NamespaceReaderTest(unittest.TestCase):
+    site_dir = str(pathlib.Path(__file__).parent)
+
+    @classmethod
+    def setUpClass(cls):
+        sys.path.append(cls.site_dir)
+
+    @classmethod
+    def tearDownClass(cls):
+        sys.path.remove(cls.site_dir)
+
+    def test_init_error(self):
+        with self.assertRaises(ValueError):
+            NamespaceReader(['path1', 'path2'])
+
+    def test_resource_path(self):
+        namespacedata01 = import_module('namespacedata01')
+        reader = NamespaceReader(namespacedata01.__spec__.submodule_search_locations)
+
+        root = os.path.abspath(os.path.join(__file__, '..', 'namespacedata01'))
+        self.assertEqual(
+            reader.resource_path('binary.file'), os.path.join(root, 'binary.file')
+        )
+        self.assertEqual(
+            reader.resource_path('imaginary'), os.path.join(root, 'imaginary')
+        )
+
+    def test_files(self):
+        namespacedata01 = import_module('namespacedata01')
+        reader = NamespaceReader(namespacedata01.__spec__.submodule_search_locations)
+        root = os.path.abspath(os.path.join(__file__, '..', 'namespacedata01'))
+        self.assertIsInstance(reader.files(), MultiplexedPath)
+        self.assertEqual(repr(reader.files()), f"MultiplexedPath('{root}')")
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/libs/importlib_resources/tests/test_resource.py b/libs/importlib_resources/tests/test_resource.py
new file mode 100644
index 000000000..823902716
--- /dev/null
+++ b/libs/importlib_resources/tests/test_resource.py
@@ -0,0 +1,260 @@
+import sys
+import unittest
+import importlib_resources as resources
+import uuid
+import pathlib
+
+from . import data01
+from . import zipdata01, zipdata02
+from . import util
+from importlib import import_module
+from ._compat import import_helper, unlink
+
+
+class ResourceTests:
+    # Subclasses are expected to set the `data` attribute.
+
+    def test_is_file_exists(self):
+        target = resources.files(self.data) / 'binary.file'
+        self.assertTrue(target.is_file())
+
+    def test_is_file_missing(self):
+        target = resources.files(self.data) / 'not-a-file'
+        self.assertFalse(target.is_file())
+
+    def test_is_dir(self):
+        target = resources.files(self.data) / 'subdirectory'
+        self.assertFalse(target.is_file())
+        self.assertTrue(target.is_dir())
+
+
+class ResourceDiskTests(ResourceTests, unittest.TestCase):
+    def setUp(self):
+        self.data = data01
+
+
+class ResourceZipTests(ResourceTests, util.ZipSetup, unittest.TestCase):
+    pass
+
+
+def names(traversable):
+    return {item.name for item in traversable.iterdir()}
+
+
+class ResourceLoaderTests(unittest.TestCase):
+    def test_resource_contents(self):
+        package = util.create_package(
+            file=data01, path=data01.__file__, contents=['A', 'B', 'C']
+        )
+        self.assertEqual(names(resources.files(package)), {'A', 'B', 'C'})
+
+    def test_is_file(self):
+        package = util.create_package(
+            file=data01, path=data01.__file__, contents=['A', 'B', 'C', 'D/E', 'D/F']
+        )
+        self.assertTrue(resources.files(package).joinpath('B').is_file())
+
+    def test_is_dir(self):
+        package = util.create_package(
+            file=data01, path=data01.__file__, contents=['A', 'B', 'C', 'D/E', 'D/F']
+        )
+        self.assertTrue(resources.files(package).joinpath('D').is_dir())
+
+    def test_resource_missing(self):
+        package = util.create_package(
+            file=data01, path=data01.__file__, contents=['A', 'B', 'C', 'D/E', 'D/F']
+        )
+        self.assertFalse(resources.files(package).joinpath('Z').is_file())
+
+
+class ResourceCornerCaseTests(unittest.TestCase):
+    def test_package_has_no_reader_fallback(self):
+        # Test odd ball packages which:
+        # 1. Do not have a ResourceReader as a loader
+        # 2. Are not on the file system
+        # 3. Are not in a zip file
+        module = util.create_package(
+            file=data01, path=data01.__file__, contents=['A', 'B', 'C']
+        )
+        # Give the module a dummy loader.
+        module.__loader__ = object()
+        # Give the module a dummy origin.
+        module.__file__ = '/path/which/shall/not/be/named'
+        module.__spec__.loader = module.__loader__
+        module.__spec__.origin = module.__file__
+        self.assertFalse(resources.files(module).joinpath('A').is_file())
+
+
+class ResourceFromZipsTest01(util.ZipSetupBase, unittest.TestCase):
+    ZIP_MODULE = zipdata01  # type: ignore
+
+    def test_is_submodule_resource(self):
+        submodule = import_module('ziptestdata.subdirectory')
+        self.assertTrue(resources.files(submodule).joinpath('binary.file').is_file())
+
+    def test_read_submodule_resource_by_name(self):
+        self.assertTrue(
+            resources.files('ziptestdata.subdirectory')
+            .joinpath('binary.file')
+            .is_file()
+        )
+
+    def test_submodule_contents(self):
+        submodule = import_module('ziptestdata.subdirectory')
+        self.assertEqual(
+            names(resources.files(submodule)), {'__init__.py', 'binary.file'}
+        )
+
+    def test_submodule_contents_by_name(self):
+        self.assertEqual(
+            names(resources.files('ziptestdata.subdirectory')),
+            {'__init__.py', 'binary.file'},
+        )
+
+    def test_as_file_directory(self):
+        with resources.as_file(resources.files('ziptestdata')) as data:
+            assert data.name == 'ziptestdata'
+            assert data.is_dir()
+            assert data.joinpath('subdirectory').is_dir()
+            assert len(list(data.iterdir()))
+        assert not data.parent.exists()
+
+
+class ResourceFromZipsTest02(util.ZipSetupBase, unittest.TestCase):
+    ZIP_MODULE = zipdata02  # type: ignore
+
+    def test_unrelated_contents(self):
+        """
+        Test thata zip with two unrelated subpackages return
+        distinct resources. Ref python/importlib_resources#44.
+        """
+        self.assertEqual(
+            names(resources.files('ziptestdata.one')),
+            {'__init__.py', 'resource1.txt'},
+        )
+        self.assertEqual(
+            names(resources.files('ziptestdata.two')),
+            {'__init__.py', 'resource2.txt'},
+        )
+
+
+class DeletingZipsTest(unittest.TestCase):
+    """Having accessed resources in a zip file should not keep an open
+    reference to the zip.
+    """
+
+    ZIP_MODULE = zipdata01
+
+    def setUp(self):
+        modules = import_helper.modules_setup()
+        self.addCleanup(import_helper.modules_cleanup, *modules)
+
+        data_path = pathlib.Path(self.ZIP_MODULE.__file__)
+        data_dir = data_path.parent
+        self.source_zip_path = data_dir / 'ziptestdata.zip'
+        self.zip_path = pathlib.Path(f'{uuid.uuid4()}.zip').absolute()
+        self.zip_path.write_bytes(self.source_zip_path.read_bytes())
+        sys.path.append(str(self.zip_path))
+        self.data = import_module('ziptestdata')
+
+    def tearDown(self):
+        try:
+            sys.path.remove(str(self.zip_path))
+        except ValueError:
+            pass
+
+        try:
+            del sys.path_importer_cache[str(self.zip_path)]
+            del sys.modules[self.data.__name__]
+        except KeyError:
+            pass
+
+        try:
+            unlink(self.zip_path)
+        except OSError:
+            # If the test fails, this will probably fail too
+            pass
+
+    def test_iterdir_does_not_keep_open(self):
+        c = [item.name for item in resources.files('ziptestdata').iterdir()]
+        self.zip_path.unlink()
+        del c
+
+    def test_is_file_does_not_keep_open(self):
+        c = resources.files('ziptestdata').joinpath('binary.file').is_file()
+        self.zip_path.unlink()
+        del c
+
+    def test_is_file_failure_does_not_keep_open(self):
+        c = resources.files('ziptestdata').joinpath('not-present').is_file()
+        self.zip_path.unlink()
+        del c
+
+    @unittest.skip("Desired but not supported.")
+    def test_as_file_does_not_keep_open(self):  # pragma: no cover
+        c = resources.as_file(resources.files('ziptestdata') / 'binary.file')
+        self.zip_path.unlink()
+        del c
+
+    def test_entered_path_does_not_keep_open(self):
+        # This is what certifi does on import to make its bundle
+        # available for the process duration.
+        c = resources.as_file(
+            resources.files('ziptestdata') / 'binary.file'
+        ).__enter__()
+        self.zip_path.unlink()
+        del c
+
+    def test_read_binary_does_not_keep_open(self):
+        c = resources.files('ziptestdata').joinpath('binary.file').read_bytes()
+        self.zip_path.unlink()
+        del c
+
+    def test_read_text_does_not_keep_open(self):
+        c = resources.files('ziptestdata').joinpath('utf-8.file').read_text()
+        self.zip_path.unlink()
+        del c
+
+
+class ResourceFromNamespaceTest01(unittest.TestCase):
+    site_dir = str(pathlib.Path(__file__).parent)
+
+    @classmethod
+    def setUpClass(cls):
+        sys.path.append(cls.site_dir)
+
+    @classmethod
+    def tearDownClass(cls):
+        sys.path.remove(cls.site_dir)
+
+    def test_is_submodule_resource(self):
+        self.assertTrue(
+            resources.files(import_module('namespacedata01'))
+            .joinpath('binary.file')
+            .is_file()
+        )
+
+    def test_read_submodule_resource_by_name(self):
+        self.assertTrue(
+            resources.files('namespacedata01').joinpath('binary.file').is_file()
+        )
+
+    def test_submodule_contents(self):
+        contents = names(resources.files(import_module('namespacedata01')))
+        try:
+            contents.remove('__pycache__')
+        except KeyError:
+            pass
+        self.assertEqual(contents, {'binary.file', 'utf-8.file', 'utf-16.file'})
+
+    def test_submodule_contents_by_name(self):
+        contents = names(resources.files('namespacedata01'))
+        try:
+            contents.remove('__pycache__')
+        except KeyError:
+            pass
+        self.assertEqual(contents, {'binary.file', 'utf-8.file', 'utf-16.file'})
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/libs/importlib_resources/tests/update-zips.py b/libs/importlib_resources/tests/update-zips.py
new file mode 100755
index 000000000..231334aa7
--- /dev/null
+++ b/libs/importlib_resources/tests/update-zips.py
@@ -0,0 +1,53 @@
+"""
+Generate the zip test data files.
+
+Run to build the tests/zipdataNN/ziptestdata.zip files from
+files in tests/dataNN.
+
+Replaces the file with the working copy, but does commit anything
+to the source repo.
+"""
+
+import contextlib
+import os
+import pathlib
+import zipfile
+
+
+def main():
+    """
+    >>> from unittest import mock
+    >>> monkeypatch = getfixture('monkeypatch')
+    >>> monkeypatch.setattr(zipfile, 'ZipFile', mock.MagicMock())
+    >>> print(); main()  # print workaround for bpo-32509
+    <BLANKLINE>
+    ...data01... -> ziptestdata/...
+    ...
+    ...data02... -> ziptestdata/...
+    ...
+    """
+    suffixes = '01', '02'
+    tuple(map(generate, suffixes))
+
+
+def generate(suffix):
+    root = pathlib.Path(__file__).parent.relative_to(os.getcwd())
+    zfpath = root / f'zipdata{suffix}/ziptestdata.zip'
+    with zipfile.ZipFile(zfpath, 'w') as zf:
+        for src, rel in walk(root / f'data{suffix}'):
+            dst = 'ziptestdata' / pathlib.PurePosixPath(rel.as_posix())
+            print(src, '->', dst)
+            zf.write(src, dst)
+
+
+def walk(datapath):
+    for dirpath, dirnames, filenames in os.walk(datapath):
+        with contextlib.suppress(ValueError):
+            dirnames.remove('__pycache__')
+        for filename in filenames:
+            res = pathlib.Path(dirpath) / filename
+            rel = res.relative_to(datapath)
+            yield res, rel
+
+
+__name__ == '__main__' and main()
diff --git a/libs/importlib_resources/tests/util.py b/libs/importlib_resources/tests/util.py
new file mode 100644
index 000000000..b596c0ce4
--- /dev/null
+++ b/libs/importlib_resources/tests/util.py
@@ -0,0 +1,167 @@
+import abc
+import importlib
+import io
+import sys
+import types
+import pathlib
+
+from . import data01
+from . import zipdata01
+from ..abc import ResourceReader
+from ._compat import import_helper
+
+
+from importlib.machinery import ModuleSpec
+
+
+class Reader(ResourceReader):
+    def __init__(self, **kwargs):
+        vars(self).update(kwargs)
+
+    def get_resource_reader(self, package):
+        return self
+
+    def open_resource(self, path):
+        self._path = path
+        if isinstance(self.file, Exception):
+            raise self.file
+        return self.file
+
+    def resource_path(self, path_):
+        self._path = path_
+        if isinstance(self.path, Exception):
+            raise self.path
+        return self.path
+
+    def is_resource(self, path_):
+        self._path = path_
+        if isinstance(self.path, Exception):
+            raise self.path
+
+        def part(entry):
+            return entry.split('/')
+
+        return any(
+            len(parts) == 1 and parts[0] == path_ for parts in map(part, self._contents)
+        )
+
+    def contents(self):
+        if isinstance(self.path, Exception):
+            raise self.path
+        yield from self._contents
+
+
+def create_package_from_loader(loader, is_package=True):
+    name = 'testingpackage'
+    module = types.ModuleType(name)
+    spec = ModuleSpec(name, loader, origin='does-not-exist', is_package=is_package)
+    module.__spec__ = spec
+    module.__loader__ = loader
+    return module
+
+
+def create_package(file=None, path=None, is_package=True, contents=()):
+    return create_package_from_loader(
+        Reader(file=file, path=path, _contents=contents),
+        is_package,
+    )
+
+
+class CommonTests(metaclass=abc.ABCMeta):
+    """
+    Tests shared by test_open, test_path, and test_read.
+    """
+
+    @abc.abstractmethod
+    def execute(self, package, path):
+        """
+        Call the pertinent legacy API function (e.g. open_text, path)
+        on package and path.
+        """
+
+    def test_package_name(self):
+        # Passing in the package name should succeed.
+        self.execute(data01.__name__, 'utf-8.file')
+
+    def test_package_object(self):
+        # Passing in the package itself should succeed.
+        self.execute(data01, 'utf-8.file')
+
+    def test_string_path(self):
+        # Passing in a string for the path should succeed.
+        path = 'utf-8.file'
+        self.execute(data01, path)
+
+    def test_pathlib_path(self):
+        # Passing in a pathlib.PurePath object for the path should succeed.
+        path = pathlib.PurePath('utf-8.file')
+        self.execute(data01, path)
+
+    def test_importing_module_as_side_effect(self):
+        # The anchor package can already be imported.
+        del sys.modules[data01.__name__]
+        self.execute(data01.__name__, 'utf-8.file')
+
+    def test_missing_path(self):
+        # Attempting to open or read or request the path for a
+        # non-existent path should succeed if open_resource
+        # can return a viable data stream.
+        bytes_data = io.BytesIO(b'Hello, world!')
+        package = create_package(file=bytes_data, path=FileNotFoundError())
+        self.execute(package, 'utf-8.file')
+        self.assertEqual(package.__loader__._path, 'utf-8.file')
+
+    def test_extant_path(self):
+        # Attempting to open or read or request the path when the
+        # path does exist should still succeed. Does not assert
+        # anything about the result.
+        bytes_data = io.BytesIO(b'Hello, world!')
+        # any path that exists
+        path = __file__
+        package = create_package(file=bytes_data, path=path)
+        self.execute(package, 'utf-8.file')
+        self.assertEqual(package.__loader__._path, 'utf-8.file')
+
+    def test_useless_loader(self):
+        package = create_package(file=FileNotFoundError(), path=FileNotFoundError())
+        with self.assertRaises(FileNotFoundError):
+            self.execute(package, 'utf-8.file')
+
+
+class ZipSetupBase:
+    ZIP_MODULE = None
+
+    @classmethod
+    def setUpClass(cls):
+        data_path = pathlib.Path(cls.ZIP_MODULE.__file__)
+        data_dir = data_path.parent
+        cls._zip_path = str(data_dir / 'ziptestdata.zip')
+        sys.path.append(cls._zip_path)
+        cls.data = importlib.import_module('ziptestdata')
+
+    @classmethod
+    def tearDownClass(cls):
+        try:
+            sys.path.remove(cls._zip_path)
+        except ValueError:
+            pass
+
+        try:
+            del sys.path_importer_cache[cls._zip_path]
+            del sys.modules[cls.data.__name__]
+        except KeyError:
+            pass
+
+        try:
+            del cls.data
+            del cls._zip_path
+        except AttributeError:
+            pass
+
+    def setUp(self):
+        modules = import_helper.modules_setup()
+        self.addCleanup(import_helper.modules_cleanup, *modules)
+
+
+class ZipSetup(ZipSetupBase):
+    ZIP_MODULE = zipdata01  # type: ignore
diff --git a/libs/importlib_resources/tests/zipdata01/__init__.py b/libs/importlib_resources/tests/zipdata01/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libs/importlib_resources/tests/zipdata01/__init__.py
diff --git a/libs/importlib_resources/tests/zipdata01/ziptestdata.zip b/libs/importlib_resources/tests/zipdata01/ziptestdata.zip
new file mode 100644
index 000000000..9a3bb0739
--- /dev/null
+++ b/libs/importlib_resources/tests/zipdata01/ziptestdata.zip
diff --git a/libs/importlib_resources/tests/zipdata02/__init__.py b/libs/importlib_resources/tests/zipdata02/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libs/importlib_resources/tests/zipdata02/__init__.py
diff --git a/libs/importlib_resources/tests/zipdata02/ziptestdata.zip b/libs/importlib_resources/tests/zipdata02/ziptestdata.zip
new file mode 100644
index 000000000..d63ff512d
--- /dev/null
+++ b/libs/importlib_resources/tests/zipdata02/ziptestdata.zip