--- /dev/null
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fstest
+
+import (
+ "io"
+ "io/fs"
+ "path"
+ "sort"
+ "strings"
+ "time"
+)
+
+// A MapFS is a simple in-memory file system for use in tests,
+// represented as a map from path names (arguments to Open)
+// to information about the files or directories they represent.
+//
+// The map need not include parent directories for files contained
+// in the map; those will be synthesized if needed.
+// But a directory can still be included by setting the MapFile.Mode's ModeDir bit;
+// this may be necessary for detailed control over the directory's FileInfo
+// or to create an empty directory.
+//
+// File system operations read directly from the map,
+// so that the file system can be changed by editing the map as needed.
+// An implication is that file system operations must not run concurrently
+// with changes to the map, which would be a race.
+// Another implication is that opening or reading a directory requires
+// iterating over the entire map, so a MapFS should typically be used with not more
+// than a few hundred entries or directory reads.
+type MapFS map[string]*MapFile
+
+// A MapFile describes a single file in a MapFS.
+type MapFile struct {
+ Data []byte // file content
+ Mode fs.FileMode // FileInfo.Mode
+ ModTime time.Time // FileInfo.ModTime
+ Sys interface{} // FileInfo.Sys
+}
+
+var _ fs.FS = MapFS(nil)
+var _ fs.File = (*openMapFile)(nil)
+
+// Open opens the named file.
+func (fsys MapFS) Open(name string) (fs.File, error) {
+ if !fs.ValidPath(name) {
+ return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
+ }
+ file := fsys[name]
+ if file != nil && file.Mode&fs.ModeDir == 0 {
+ // Ordinary file
+ return &openMapFile{name, mapFileInfo{path.Base(name), file}, 0}, nil
+ }
+
+ // Directory, possibly synthesized.
+ // Note that file can be nil here: the map need not contain explicit parent directories for all its files.
+ // But file can also be non-nil, in case the user wants to set metadata for the directory explicitly.
+ // Either way, we need to construct the list of children of this directory.
+ var list []mapFileInfo
+ var elem string
+ var need = make(map[string]bool)
+ if name == "." {
+ elem = "."
+ for fname, f := range fsys {
+ i := strings.Index(fname, "/")
+ if i < 0 {
+ list = append(list, mapFileInfo{fname, f})
+ } else {
+ need[fname[:i]] = true
+ }
+ }
+ } else {
+ elem = name[strings.LastIndex(name, "/")+1:]
+ prefix := name + "/"
+ for fname, f := range fsys {
+ if strings.HasPrefix(fname, prefix) {
+ felem := fname[len(prefix):]
+ i := strings.Index(felem, "/")
+ if i < 0 {
+ list = append(list, mapFileInfo{felem, f})
+ } else {
+ need[fname[len(prefix):len(prefix)+i]] = true
+ }
+ }
+ }
+ // If the directory name is not in the map,
+ // and there are no children of the name in the map,
+ // then the directory is treated as not existing.
+ if file == nil && list == nil && len(need) == 0 {
+ return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
+ }
+ }
+ for _, fi := range list {
+ delete(need, fi.name)
+ }
+ for name := range need {
+ list = append(list, mapFileInfo{name, &MapFile{Mode: fs.ModeDir}})
+ }
+ sort.Slice(list, func(i, j int) bool {
+ return list[i].name < list[j].name
+ })
+
+ if file == nil {
+ file = &MapFile{Mode: fs.ModeDir}
+ }
+ return &mapDir{name, mapFileInfo{elem, file}, list, 0}, nil
+}
+
+// A mapFileInfo implements fs.FileInfo and fs.DirEntry for a given map file.
+type mapFileInfo struct {
+ name string
+ f *MapFile
+}
+
+func (i *mapFileInfo) Name() string { return i.name }
+func (i *mapFileInfo) Size() int64 { return int64(len(i.f.Data)) }
+func (i *mapFileInfo) Mode() fs.FileMode { return i.f.Mode }
+func (i *mapFileInfo) Type() fs.FileMode { return i.f.Mode.Type() }
+func (i *mapFileInfo) ModTime() time.Time { return i.f.ModTime }
+func (i *mapFileInfo) IsDir() bool { return i.f.Mode&fs.ModeDir != 0 }
+func (i *mapFileInfo) Sys() interface{} { return i.f.Sys }
+func (i *mapFileInfo) Info() (fs.FileInfo, error) { return i, nil }
+
+// An openMapFile is a regular (non-directory) fs.File open for reading.
+type openMapFile struct {
+ path string
+ mapFileInfo
+ offset int64
+}
+
+func (f *openMapFile) Stat() (fs.FileInfo, error) { return &f.mapFileInfo, nil }
+
+func (f *openMapFile) Close() error { return nil }
+
+func (f *openMapFile) Read(b []byte) (int, error) {
+ if f.offset >= int64(len(f.f.Data)) {
+ return 0, io.EOF
+ }
+ if f.offset < 0 {
+ return 0, &fs.PathError{Op: "read", Path: f.path, Err: fs.ErrInvalid}
+ }
+ n := copy(b, f.f.Data[f.offset:])
+ f.offset += int64(n)
+ return n, nil
+}
+
+func (f *openMapFile) Seek(offset int64, whence int) (int64, error) {
+ switch whence {
+ case 0:
+ // offset += 0
+ case 1:
+ offset += f.offset
+ case 2:
+ offset += int64(len(f.f.Data))
+ }
+ if offset < 0 || offset > int64(len(f.f.Data)) {
+ return 0, &fs.PathError{Op: "seek", Path: f.path, Err: fs.ErrInvalid}
+ }
+ f.offset = offset
+ return offset, nil
+}
+
+func (f *openMapFile) ReadAt(b []byte, offset int64) (int, error) {
+ if offset < 0 || offset > int64(len(f.f.Data)) {
+ return 0, &fs.PathError{Op: "read", Path: f.path, Err: fs.ErrInvalid}
+ }
+ n := copy(b, f.f.Data[offset:])
+ if n < len(b) {
+ return n, io.EOF
+ }
+ return n, nil
+}
+
+// A mapDir is a directory fs.File (so also an fs.ReadDirFile) open for reading.
+type mapDir struct {
+ path string
+ mapFileInfo
+ entry []mapFileInfo
+ offset int
+}
+
+func (d *mapDir) Stat() (fs.FileInfo, error) { return &d.mapFileInfo, nil }
+func (d *mapDir) Close() error { return nil }
+func (d *mapDir) Read(b []byte) (int, error) {
+ return 0, &fs.PathError{Op: "read", Path: d.path, Err: fs.ErrInvalid}
+}
+
+func (d *mapDir) ReadDir(count int) ([]fs.DirEntry, error) {
+ n := len(d.entry) - d.offset
+ if count > 0 && n > count {
+ n = count
+ }
+ if n == 0 && count > 0 {
+ return nil, io.EOF
+ }
+ list := make([]fs.DirEntry, n)
+ for i := range list {
+ list[i] = &d.entry[d.offset+i]
+ }
+ d.offset += n
+ return list, nil
+}
--- /dev/null
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package fstest implements support for testing implementations and users of file systems.
+package fstest
+
+import (
+ "errors"
+ "fmt"
+ "io"
+ "io/fs"
+ "io/ioutil"
+ "sort"
+ "strings"
+ "testing/iotest"
+)
+
+// TestFS tests a file system implementation.
+// It walks the entire tree of files in fsys,
+// opening and checking that each file behaves correctly.
+// It also checks that the file system contains at least the expected files.
+//
+// If TestFS finds any misbehaviors, it returns an error reporting all of them.
+// The error text spans multiple lines, one per detected misbehavior.
+//
+// Typical usage inside a test is:
+//
+// if err := fstest.TestFS(myFS, "file/that/should/be/present"); err != nil {
+// t.Fatal(err)
+// }
+//
+func TestFS(fsys fs.FS, expected ...string) error {
+ t := fsTester{fsys: fsys}
+ t.checkDir(".")
+ t.checkOpen(".")
+ found := make(map[string]bool)
+ for _, dir := range t.dirs {
+ found[dir] = true
+ }
+ for _, file := range t.files {
+ found[file] = true
+ }
+ for _, name := range expected {
+ if !found[name] {
+ t.errorf("expected but not found: %s", name)
+ }
+ }
+ if len(t.errText) == 0 {
+ return nil
+ }
+ return errors.New("TestFS found errors:\n" + string(t.errText))
+}
+
+// An fsTester holds state for running the test.
+type fsTester struct {
+ fsys fs.FS
+ errText []byte
+ dirs []string
+ files []string
+}
+
+// errorf adds an error line to errText.
+func (t *fsTester) errorf(format string, args ...interface{}) {
+ if len(t.errText) > 0 {
+ t.errText = append(t.errText, '\n')
+ }
+ t.errText = append(t.errText, fmt.Sprintf(format, args...)...)
+}
+
+func (t *fsTester) openDir(dir string) fs.ReadDirFile {
+ f, err := t.fsys.Open(dir)
+ if err != nil {
+ t.errorf("%s: Open: %v", dir, err)
+ return nil
+ }
+ d, ok := f.(fs.ReadDirFile)
+ if !ok {
+ f.Close()
+ t.errorf("%s: Open returned File type %T, not a io.ReadDirFile", dir, f)
+ return nil
+ }
+ return d
+}
+
+// checkDir checks the directory dir, which is expected to exist
+// (it is either the root or was found in a directory listing with IsDir true).
+func (t *fsTester) checkDir(dir string) {
+ // Read entire directory.
+ t.dirs = append(t.dirs, dir)
+ d := t.openDir(dir)
+ if d == nil {
+ return
+ }
+ list, err := d.ReadDir(-1)
+ if err != nil {
+ d.Close()
+ t.errorf("%s: ReadDir(-1): %v", dir, err)
+ return
+ }
+
+ // Check all children.
+ var prefix string
+ if dir == "." {
+ prefix = ""
+ } else {
+ prefix = dir + "/"
+ }
+ for _, info := range list {
+ name := info.Name()
+ switch {
+ case name == ".", name == "..", name == "":
+ t.errorf("%s: ReadDir: child has invalid name: %#q", dir, name)
+ continue
+ case strings.Contains(name, "/"):
+ t.errorf("%s: ReadDir: child name contains slash: %#q", dir, name)
+ continue
+ case strings.Contains(name, `\`):
+ t.errorf("%s: ReadDir: child name contains backslash: %#q", dir, name)
+ continue
+ }
+ path := prefix + name
+ t.checkStat(path, info)
+ t.checkOpen(path)
+ if info.IsDir() {
+ t.checkDir(path)
+ } else {
+ t.checkFile(path)
+ }
+ }
+
+ // Check ReadDir(-1) at EOF.
+ list2, err := d.ReadDir(-1)
+ if len(list2) > 0 || err != nil {
+ d.Close()
+ t.errorf("%s: ReadDir(-1) at EOF = %d entries, %v, wanted 0 entries, nil", dir, len(list2), err)
+ return
+ }
+
+ // Check ReadDir(1) at EOF (different results).
+ list2, err = d.ReadDir(1)
+ if len(list2) > 0 || err != io.EOF {
+ d.Close()
+ t.errorf("%s: ReadDir(1) at EOF = %d entries, %v, wanted 0 entries, EOF", dir, len(list2), err)
+ return
+ }
+
+ // Check that close does not report an error.
+ if err := d.Close(); err != nil {
+ t.errorf("%s: Close: %v", dir, err)
+ }
+
+ // Check that closing twice doesn't crash.
+ // The return value doesn't matter.
+ d.Close()
+
+ // Reopen directory, read a second time, make sure contents match.
+ if d = t.openDir(dir); d == nil {
+ return
+ }
+ defer d.Close()
+ list2, err = d.ReadDir(-1)
+ if err != nil {
+ t.errorf("%s: second Open+ReadDir(-1): %v", dir, err)
+ return
+ }
+ t.checkDirList(dir, "first Open+ReadDir(-1) vs second Open+ReadDir(-1)", list, list2)
+
+ // Reopen directory, read a third time in pieces, make sure contents match.
+ if d = t.openDir(dir); d == nil {
+ return
+ }
+ defer d.Close()
+ list2 = nil
+ for {
+ n := 1
+ if len(list2) > 0 {
+ n = 2
+ }
+ frag, err := d.ReadDir(n)
+ if len(frag) > n {
+ t.errorf("%s: third Open: ReadDir(%d) after %d: %d entries (too many)", dir, n, len(list2), len(frag))
+ return
+ }
+ list2 = append(list2, frag...)
+ if err == io.EOF {
+ break
+ }
+ if err != nil {
+ t.errorf("%s: third Open: ReadDir(%d) after %d: %v", dir, n, len(list2), err)
+ return
+ }
+ if n == 0 {
+ t.errorf("%s: third Open: ReadDir(%d) after %d: 0 entries but nil error", dir, n, len(list2))
+ return
+ }
+ }
+ t.checkDirList(dir, "first Open+ReadDir(-1) vs third Open+ReadDir(1,2) loop", list, list2)
+}
+
+// formatEntry formats an fs.DirEntry into a string for error messages and comparison.
+func formatEntry(entry fs.DirEntry) string {
+ return fmt.Sprintf("%s IsDir=%v Type=%v", entry.Name(), entry.IsDir(), entry.Type())
+}
+
+// formatInfoEntry formats an fs.FileInfo into a string like the result of formatEntry, for error messages and comparison.
+func formatInfoEntry(info fs.FileInfo) string {
+ return fmt.Sprintf("%s IsDir=%v Type=%v", info.Name(), info.IsDir(), info.Mode().Type())
+}
+
+// formatInfo formats an fs.FileInfo into a string for error messages and comparison.
+func formatInfo(info fs.FileInfo) string {
+ return fmt.Sprintf("%s IsDir=%v Mode=%v Size=%d ModTime=%v", info.Name(), info.IsDir(), info.Mode(), info.Size(), info.ModTime())
+}
+
+// checkStat checks that a direct stat of path matches entry,
+// which was found in the parent's directory listing.
+func (t *fsTester) checkStat(path string, entry fs.DirEntry) {
+ file, err := t.fsys.Open(path)
+ if err != nil {
+ t.errorf("%s: Open: %v", path, err)
+ return
+ }
+ info, err := file.Stat()
+ file.Close()
+ if err != nil {
+ t.errorf("%s: Stat: %v", path, err)
+ return
+ }
+ fentry := formatEntry(entry)
+ finfo := formatInfoEntry(info)
+ if fentry != finfo {
+ t.errorf("%s: mismatch:\n\tentry = %v\n\tfile.Stat() = %v", path, fentry, finfo)
+ }
+}
+
+// checkDirList checks that two directory lists contain the same files and file info.
+// The order of the lists need not match.
+func (t *fsTester) checkDirList(dir, desc string, list1, list2 []fs.DirEntry) {
+ old := make(map[string]fs.DirEntry)
+ checkMode := func(entry fs.DirEntry) {
+ if entry.IsDir() != (entry.Type()&fs.ModeDir != 0) {
+ if entry.IsDir() {
+ t.errorf("%s: ReadDir returned %s with IsDir() = true, Type() & ModeDir = 0", dir, entry.Name())
+ } else {
+ t.errorf("%s: ReadDir returned %s with IsDir() = false, Type() & ModeDir = ModeDir", dir, entry.Name())
+ }
+ }
+ }
+
+ for _, entry1 := range list1 {
+ old[entry1.Name()] = entry1
+ checkMode(entry1)
+ }
+
+ var diffs []string
+ for _, entry2 := range list2 {
+ entry1 := old[entry2.Name()]
+ if entry1 == nil {
+ checkMode(entry2)
+ diffs = append(diffs, "+ "+formatEntry(entry2))
+ continue
+ }
+ if formatEntry(entry1) != formatEntry(entry2) {
+ diffs = append(diffs, "- "+formatEntry(entry1), "+ "+formatEntry(entry2))
+ }
+ delete(old, entry2.Name())
+ }
+ for _, entry1 := range old {
+ diffs = append(diffs, "- "+formatEntry(entry1))
+ }
+
+ if len(diffs) == 0 {
+ return
+ }
+
+ sort.Slice(diffs, func(i, j int) bool {
+ fi := strings.Fields(diffs[i])
+ fj := strings.Fields(diffs[j])
+ // sort by name (i < j) and then +/- (j < i, because + < -)
+ return fi[1]+" "+fj[0] < fj[1]+" "+fi[0]
+ })
+
+ t.errorf("%s: diff %s:\n\t%s", dir, desc, strings.Join(diffs, "\n\t"))
+}
+
+// checkFile checks that basic file reading works correctly.
+func (t *fsTester) checkFile(file string) {
+ t.files = append(t.files, file)
+
+ // Read entire file.
+ f, err := t.fsys.Open(file)
+ if err != nil {
+ t.errorf("%s: Open: %v", file, err)
+ return
+ }
+
+ data, err := ioutil.ReadAll(f)
+ if err != nil {
+ f.Close()
+ t.errorf("%s: Open+ReadAll: %v", file, err)
+ return
+ }
+
+ if err := f.Close(); err != nil {
+ t.errorf("%s: Close: %v", file, err)
+ }
+
+ // Check that closing twice doesn't crash.
+ // The return value doesn't matter.
+ f.Close()
+
+ // Use iotest.TestReader to check small reads, Seek, ReadAt.
+ f, err = t.fsys.Open(file)
+ if err != nil {
+ t.errorf("%s: second Open: %v", file, err)
+ return
+ }
+ defer f.Close()
+ if err := iotest.TestReader(f, data); err != nil {
+ t.errorf("%s: failed TestReader:\n\t%s", file, strings.ReplaceAll(err.Error(), "\n", "\n\t"))
+ }
+}
+
+func (t *fsTester) checkFileRead(file, desc string, data1, data2 []byte) {
+ if string(data1) != string(data2) {
+ t.errorf("%s: %s: different data returned\n\t%q\n\t%q", file, desc, data1, data2)
+ return
+ }
+}
+
+// checkOpen checks that various invalid forms of file's name cannot be opened.
+func (t *fsTester) checkOpen(file string) {
+ bad := []string{
+ "/" + file,
+ file + "/.",
+ }
+ if file == "." {
+ bad = append(bad, "/")
+ }
+ if i := strings.Index(file, "/"); i >= 0 {
+ bad = append(bad,
+ file[:i]+"//"+file[i+1:],
+ file[:i]+"/./"+file[i+1:],
+ file[:i]+`\`+file[i+1:],
+ file[:i]+"/../"+file,
+ )
+ }
+ if i := strings.LastIndex(file, "/"); i >= 0 {
+ bad = append(bad,
+ file[:i]+"//"+file[i+1:],
+ file[:i]+"/./"+file[i+1:],
+ file[:i]+`\`+file[i+1:],
+ file+"/../"+file[i+1:],
+ )
+ }
+
+ for _, b := range bad {
+ if f, err := t.fsys.Open(b); err == nil {
+ f.Close()
+ t.errorf("%s: Open(%s) succeeded, want error", file, b)
+ }
+ }
+}