Fix and add integration test for the Bootstrap SCSS module for both Dart Sass and Libsass

This fixes the reverse filesystem lookup (absolute filename to path relative to the composite filesystem).

The old logic had some assumptions about the locality of the actual files that didn't work in more complex scenarios.

This commit now also adds the popular Bootstrap SCSS Hugo module to the CI build (both for libsass and dartsass transpiler), so we can hopefully avoid similar future breakage.

Fixes #12178

7 files changed, 135 insertions, 37 deletions

diff --git a/hugofs/rootmapping_fs.go b/hugofs/rootmapping_fs.go
index a5bf9aadf..336c8b4e7 100644
--- a/hugofs/rootmapping_fs.go
+++ b/hugofs/rootmapping_fs.go
@@ -21,6 +21,7 @@ import (
 	"path"
 	"path/filepath"
 	"strings"
+	"sync/atomic"
 
 	"github.com/gohugoio/hugo/common/herrors"
 	"github.com/gohugoio/hugo/common/paths"
@@ -43,6 +44,7 @@ var _ ReverseLookupProvder = (*RootMappingFs)(nil)
 func NewRootMappingFs(fs afero.Fs, rms ...RootMapping) (*RootMappingFs, error) {
 	rootMapToReal := radix.New()
 	realMapToRoot := radix.New()
+	id := fmt.Sprintf("rfs-%d", rootMappingFsCounter.Add(1))
 
 	addMapping := func(key string, rm RootMapping, to *radix.Tree) {
 		var mappings []RootMapping
@@ -76,6 +78,16 @@ func NewRootMappingFs(fs afero.Fs, rms ...RootMapping) (*RootMappingFs, error) {
 			rm.Meta = NewFileMeta()
 		}
 
+		if rm.FromBase == "" {
+			panic(" rm.FromBase is empty")
+		}
+
+		rm.Meta.Component = rm.FromBase
+		rm.Meta.Module = rm.Module
+		rm.Meta.ModuleOrdinal = rm.ModuleOrdinal
+		rm.Meta.IsProject = rm.IsProject
+		rm.Meta.BaseDir = rm.ToBase
+
 		if !fi.IsDir() {
 			// We do allow single file mounts.
 			// However, the file system logic will be much simpler with just directories.
@@ -122,19 +134,9 @@ func NewRootMappingFs(fs afero.Fs, rms ...RootMapping) (*RootMappingFs, error) {
 			}
 		}
 
-		if rm.FromBase == "" {
-			panic(" rm.FromBase is empty")
-		}
-
 		// Extract "blog" from "content/blog"
 		rm.path = strings.TrimPrefix(strings.TrimPrefix(rm.From, rm.FromBase), filepathSeparator)
-
 		rm.Meta.SourceRoot = fi.(MetaProvider).Meta().Filename
-		rm.Meta.BaseDir = rm.ToBase
-		rm.Meta.Module = rm.Module
-		rm.Meta.ModuleOrdinal = rm.ModuleOrdinal
-		rm.Meta.Component = rm.FromBase
-		rm.Meta.IsProject = rm.IsProject
 
 		meta := rm.Meta.Copy()
 
@@ -156,6 +158,7 @@ func NewRootMappingFs(fs afero.Fs, rms ...RootMapping) (*RootMappingFs, error) {
 	}
 
 	rfs := &RootMappingFs{
+		id:            id,
 		Fs:            fs,
 		rootMapToReal: rootMapToReal,
 		realMapToRoot: realMapToRoot,
@@ -227,11 +230,14 @@ var _ FilesystemUnwrapper = (*RootMappingFs)(nil)
 // is directories only, and they will be returned in Readdir and Readdirnames
 // in the order given.
 type RootMappingFs struct {
+	id string
 	afero.Fs
 	rootMapToReal *radix.Tree
 	realMapToRoot *radix.Tree
 }
 
+var rootMappingFsCounter atomic.Int32
+
 func (fs *RootMappingFs) Mounts(base string) ([]FileMetaInfo, error) {
 	base = filepathSeparator + fs.cleanName(base)
 	roots := fs.getRootsWithPrefix(base)
@@ -263,6 +269,10 @@ func (fs *RootMappingFs) Mounts(base string) ([]FileMetaInfo, error) {
 	return fss, nil
 }
 
+func (fs *RootMappingFs) Key() string {
+	return fs.id
+}
+
 func (fs *RootMappingFs) UnwrapFilesystem() afero.Fs {
 	return fs.Fs
 }
@@ -320,16 +330,16 @@ func (c ComponentPath) ComponentPathJoined() string {
 }
 
 type ReverseLookupProvder interface {
-	ReverseLookup(filename string, checkExists bool) ([]ComponentPath, error)
-	ReverseLookupComponent(component, filename string, checkExists bool) ([]ComponentPath, error)
+	ReverseLookup(filename string) ([]ComponentPath, error)
+	ReverseLookupComponent(component, filename string) ([]ComponentPath, error)
 }
 
 // func (fs *RootMappingFs) ReverseStat(filename string) ([]FileMetaInfo, error)
-func (fs *RootMappingFs) ReverseLookup(filename string, checkExists bool) ([]ComponentPath, error) {
-	return fs.ReverseLookupComponent("", filename, checkExists)
+func (fs *RootMappingFs) ReverseLookup(filename string) ([]ComponentPath, error) {
+	return fs.ReverseLookupComponent("", filename)
 }
 
-func (fs *RootMappingFs) ReverseLookupComponent(component, filename string, checkExists bool) ([]ComponentPath, error) {
+func (fs *RootMappingFs) ReverseLookupComponent(component, filename string) ([]ComponentPath, error) {
 	filename = fs.cleanName(filename)
 	key := filepathSeparator + filename
 
@@ -360,14 +370,6 @@ func (fs *RootMappingFs) ReverseLookupComponent(component, filename string, chec
 		} else {
 			// Now we know that this file _could_ be in this fs.
 			filename = filepathSeparator + filepath.Join(first.path, dir, name)
-
-			if checkExists {
-				// Confirm that it exists.
-				_, err := fs.Stat(first.FromBase + filename)
-				if err != nil {
-					continue
-				}
-			}
 		}
 
 		cps = append(cps, ComponentPath{
@@ -667,6 +669,7 @@ func (fs *RootMappingFs) doStat(name string) ([]FileMetaInfo, error) {
 		var fis []FileMetaInfo
 
 		for _, rm := range roots {
+
 			var fi FileMetaInfo
 			fi, err = fs.statRoot(rm, name)
 			if err == nil {
diff --git a/hugofs/rootmapping_fs_test.go b/hugofs/rootmapping_fs_test.go
index b1ef102d3..83a95d648 100644
--- a/hugofs/rootmapping_fs_test.go
+++ b/hugofs/rootmapping_fs_test.go
@@ -276,20 +276,20 @@ func TestRootMappingFsMount(t *testing.T) {
 
 	// Test ReverseLookup.
 	// Single file mounts.
-	cps, err := rfs.ReverseLookup(filepath.FromSlash("singlefiles/no.txt"), true)
+	cps, err := rfs.ReverseLookup(filepath.FromSlash("singlefiles/no.txt"))
 	c.Assert(err, qt.IsNil)
 	c.Assert(cps, qt.DeepEquals, []ComponentPath{
 		{Component: "content", Path: "singles/p1.md", Lang: "no"},
 	})
 
-	cps, err = rfs.ReverseLookup(filepath.FromSlash("singlefiles/sv.txt"), true)
+	cps, err = rfs.ReverseLookup(filepath.FromSlash("singlefiles/sv.txt"))
 	c.Assert(err, qt.IsNil)
 	c.Assert(cps, qt.DeepEquals, []ComponentPath{
 		{Component: "content", Path: "singles/p1.md", Lang: "sv"},
 	})
 
 	// File inside directory mount.
-	cps, err = rfs.ReverseLookup(filepath.FromSlash("mynoblogcontent/test.txt"), true)
+	cps, err = rfs.ReverseLookup(filepath.FromSlash("mynoblogcontent/test.txt"))
 	c.Assert(err, qt.IsNil)
 	c.Assert(cps, qt.DeepEquals, []ComponentPath{
 		{Component: "content", Path: "blog/test.txt", Lang: "no"},
diff --git a/hugolib/filesystems/basefs.go b/hugolib/filesystems/basefs.go
index aa466e0eb..b3e3284d5 100644
--- a/hugolib/filesystems/basefs.go
+++ b/hugolib/filesystems/basefs.go
@@ -265,6 +265,9 @@ type SourceFilesystem struct {
 	// This is a virtual composite filesystem. It expects path relative to a context.
 	Fs afero.Fs
 
+	// The source filesystem (usually the OS filesystem).
+	SourceFs afero.Fs
+
 	// When syncing a source folder to the target (e.g. /public), this may
 	// be set to publish into a subfolder. This is used for static syncing
 	// in multihost mode.
@@ -320,10 +323,10 @@ func (s SourceFilesystems) IsContent(filename string) bool {
 }
 
 // ResolvePaths resolves the given filename to a list of paths in the filesystems.
-func (s *SourceFilesystems) ResolvePaths(filename string, checkExists bool) []hugofs.ComponentPath {
+func (s *SourceFilesystems) ResolvePaths(filename string) []hugofs.ComponentPath {
 	var cpss []hugofs.ComponentPath
 	for _, rfs := range s.RootFss {
-		cps, err := rfs.ReverseLookup(filename, checkExists)
+		cps, err := rfs.ReverseLookup(filename)
 		if err != nil {
 			panic(err)
 		}
@@ -362,7 +365,17 @@ func (d *SourceFilesystem) ReverseLookup(filename string, checkExists bool) ([]h
 	var cps []hugofs.ComponentPath
 	hugofs.WalkFilesystems(d.Fs, func(fs afero.Fs) bool {
 		if rfs, ok := fs.(hugofs.ReverseLookupProvder); ok {
-			if c, err := rfs.ReverseLookupComponent(d.Name, filename, checkExists); err == nil {
+			if c, err := rfs.ReverseLookupComponent(d.Name, filename); err == nil {
+				if checkExists {
+					n := 0
+					for _, cp := range c {
+						if _, err := d.Fs.Stat(filepath.FromSlash(cp.Path)); err == nil {
+							c[n] = cp
+							n++
+						}
+					}
+					c = c[:n]
+				}
 				cps = append(cps, c...)
 			}
 		}
@@ -379,11 +392,12 @@ func (d *SourceFilesystem) mounts() []hugofs.FileMetaInfo {
 			if err == nil {
 				m = append(m, mounts...)
 			}
-
 		}
 		return false
 	})
+
 	// Filter out any mounts not belonging to this filesystem.
+	// TODO(bep) I think this is superflous.
 	n := 0
 	for _, mm := range m {
 		if mm.Meta().Component == d.Name {
@@ -392,6 +406,7 @@ func (d *SourceFilesystem) mounts() []hugofs.FileMetaInfo {
 		}
 	}
 	m = m[:n]
+
 	return m
 }
 
@@ -428,10 +443,8 @@ func (d *SourceFilesystem) RealDirs(from string) []string {
 		if !m.IsDir() {
 			continue
 		}
-		meta := m.Meta()
-		_, err := d.Fs.Stat(from)
-		if err == nil {
-			dirname := filepath.Join(meta.Filename, from)
+		dirname := filepath.Join(m.Meta().Filename, from)
+		if _, err := d.SourceFs.Stat(dirname); err == nil {
 			dirnames = append(dirnames, dirname)
 		}
 	}
@@ -519,8 +532,9 @@ func newSourceFilesystemsBuilder(p *paths.Paths, logger loggers.Logger, b *BaseF
 
 func (b *sourceFilesystemsBuilder) newSourceFilesystem(name string, fs afero.Fs) *SourceFilesystem {
 	return &SourceFilesystem{
-		Name: name,
-		Fs:   fs,
+		Name:     name,
+		Fs:       fs,
+		SourceFs: b.sourceFs,
 	}
 }
 
diff --git a/hugolib/hugo_sites_build.go b/hugolib/hugo_sites_build.go
index 93acdbf6b..382b1eed0 100644
--- a/hugolib/hugo_sites_build.go
+++ b/hugolib/hugo_sites_build.go
@@ -656,7 +656,7 @@ func (h *HugoSites) processPartial(ctx context.Context, l logg.LevelLogger, conf
 
 		isChangedDir := statErr == nil && fi.IsDir()
 
-		cpss := h.BaseFs.ResolvePaths(ev.Name, !removed)
+		cpss := h.BaseFs.ResolvePaths(ev.Name)
 		pss := make([]*paths.Path, len(cpss))
 		for i, cps := range cpss {
 			p := cps.Path
diff --git a/hugolib/integrationtest_builder.go b/hugolib/integrationtest_builder.go
index 642bac7ab..be11c18d6 100644
--- a/hugolib/integrationtest_builder.go
+++ b/hugolib/integrationtest_builder.go
@@ -183,6 +183,13 @@ type lockingBuffer struct {
 	bytes.Buffer
 }
 
+func (b *lockingBuffer) ReadFrom(r io.Reader) (n int64, err error) {
+	b.Lock()
+	n, err = b.Buffer.ReadFrom(r)
+	b.Unlock()
+	return
+}
+
 func (b *lockingBuffer) Write(p []byte) (n int, err error) {
 	b.Lock()
 	n, err = b.Buffer.Write(p)
diff --git a/resources/resource_transformers/tocss/dartsass/dartsass_integration_test.go b/resources/resource_transformers/tocss/dartsass/dartsass_integration_test.go
index dd4c1e5ca..4d48b3b6a 100644
--- a/resources/resource_transformers/tocss/dartsass/dartsass_integration_test.go
+++ b/resources/resource_transformers/tocss/dartsass/dartsass_integration_test.go
@@ -19,6 +19,7 @@ import (
 
 	"github.com/bep/logg"
 	qt "github.com/frankban/quicktest"
+	"github.com/gohugoio/hugo/htesting"
 	"github.com/gohugoio/hugo/hugolib"
 	"github.com/gohugoio/hugo/resources/resource_transformers/tocss/dartsass"
 )
@@ -525,3 +526,39 @@ T1: {{ $r.Content }}
 	b.AssertLogMatches(`Dart Sass: .*assets.*main.scss:13:0: number`)
 	b.AssertLogMatches(`Dart Sass: .*assets.*main.scss:14:0: number`)
 }
+
+// Note: This test is more or less duplicated in both of the SCSS packages (libsass and dartsass).
+func TestBootstrap(t *testing.T) {
+	t.Parallel()
+	if !dartsass.Supports() {
+		t.Skip()
+	}
+	if !htesting.IsCI() {
+		t.Skip("skip (slow) test in non-CI environment")
+	}
+
+	files := `
+-- hugo.toml --
+disableKinds = ["term", "taxonomy", "section", "page"]
+[module]
+[[module.imports]]
+path="github.com/gohugoio/hugo-mod-bootstrap-scss/v5"
+-- go.mod --
+module github.com/gohugoio/tests/testHugoModules
+-- assets/scss/main.scss --
+@import "bootstrap/bootstrap";
+-- layouts/index.html --
+{{ $cssOpts := (dict "transpiler" "dartsass" ) }}
+{{ $r := resources.Get "scss/main.scss" |  toCSS $cssOpts }}
+Styles: {{ $r.RelPermalink }}
+		`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			NeedsOsFS:   true,
+		}).Build()
+
+	b.AssertFileContent("public/index.html", "Styles: /scss/main.css")
+}
diff --git a/resources/resource_transformers/tocss/scss/scss_integration_test.go b/resources/resource_transformers/tocss/scss/scss_integration_test.go
index 4d7d9d710..c193ca8af 100644
--- a/resources/resource_transformers/tocss/scss/scss_integration_test.go
+++ b/resources/resource_transformers/tocss/scss/scss_integration_test.go
@@ -20,6 +20,7 @@ import (
 
 	qt "github.com/frankban/quicktest"
 
+	"github.com/gohugoio/hugo/htesting"
 	"github.com/gohugoio/hugo/hugolib"
 	"github.com/gohugoio/hugo/resources/resource_transformers/tocss/scss"
 )
@@ -290,3 +291,39 @@ T1: {{ $r.Content }}
 
 	b.AssertFileContent("public/index.html", `T1: body body{background:url(images/hero.jpg) no-repeat center/cover;font-family:Hugo's New Roman}p{color:blue;font-size:var 24px}b{color:green}`)
 }
+
+// Note: This test is more or less duplicated in both of the SCSS packages (libsass and dartsass).
+func TestBootstrap(t *testing.T) {
+	t.Parallel()
+	if !scss.Supports() {
+		t.Skip()
+	}
+	if !htesting.IsCI() {
+		t.Skip("skip (slow) test in non-CI environment")
+	}
+
+	files := `
+-- hugo.toml --
+disableKinds = ["term", "taxonomy", "section", "page"]
+[module]
+[[module.imports]]
+path="github.com/gohugoio/hugo-mod-bootstrap-scss/v5"
+-- go.mod --
+module github.com/gohugoio/tests/testHugoModules
+-- assets/scss/main.scss --
+@import "bootstrap/bootstrap";
+-- layouts/index.html --
+{{ $cssOpts := (dict "transpiler" "libsass" ) }}
+{{ $r := resources.Get "scss/main.scss" |  toCSS $cssOpts }}
+Styles: {{ $r.RelPermalink }}
+		`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			NeedsOsFS:   true,
+		}).Build()
+
+	b.AssertFileContent("public/index.html", "Styles: /scss/main.css")
+}