testfs.go

Documentation: testing/fstest

     1  // Copyright 2020 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package fstest implements support for testing implementations and users of file systems.
     6  package fstest
     7  
     8  import (
     9  	"errors"
    10  	"fmt"
    11  	"io"
    12  	"io/fs"
    13  	"path"
    14  	"reflect"
    15  	"sort"
    16  	"strings"
    17  	"testing/iotest"
    18  )
    19  
    20  // TestFS tests a file system implementation.
    21  // It walks the entire tree of files in fsys,
    22  // opening and checking that each file behaves correctly.
    23  // It also checks that the file system contains at least the expected files.
    24  // As a special case, if no expected files are listed, fsys must be empty.
    25  // Otherwise, fsys must contain at least the listed files; it can also contain others.
    26  // The contents of fsys must not change concurrently with TestFS.
    27  //
    28  // If TestFS finds any misbehaviors, it returns an error reporting all of them.
    29  // The error text spans multiple lines, one per detected misbehavior.
    30  //
    31  // Typical usage inside a test is:
    32  //
    33  //	if err := fstest.TestFS(myFS, "file/that/should/be/present"); err != nil {
    34  //		t.Fatal(err)
    35  //	}
    36  func TestFS(fsys fs.FS, expected ...string) error {
    37  	if err := testFS(fsys, expected...); err != nil {
    38  		return err
    39  	}
    40  	for _, name := range expected {
    41  		if i := strings.Index(name, "/"); i >= 0 {
    42  			dir, dirSlash := name[:i], name[:i+1]
    43  			var subExpected []string
    44  			for _, name := range expected {
    45  				if strings.HasPrefix(name, dirSlash) {
    46  					subExpected = append(subExpected, name[len(dirSlash):])
    47  				}
    48  			}
    49  			sub, err := fs.Sub(fsys, dir)
    50  			if err != nil {
    51  				return err
    52  			}
    53  			if err := testFS(sub, subExpected...); err != nil {
    54  				return fmt.Errorf("testing fs.Sub(fsys, %s): %v", dir, err)
    55  			}
    56  			break // one sub-test is enough
    57  		}
    58  	}
    59  	return nil
    60  }
    61  
    62  func testFS(fsys fs.FS, expected ...string) error {
    63  	t := fsTester{fsys: fsys}
    64  	t.checkDir(".")
    65  	t.checkOpen(".")
    66  	found := make(map[string]bool)
    67  	for _, dir := range t.dirs {
    68  		found[dir] = true
    69  	}
    70  	for _, file := range t.files {
    71  		found[file] = true
    72  	}
    73  	delete(found, ".")
    74  	if len(expected) == 0 && len(found) > 0 {
    75  		var list []string
    76  		for k := range found {
    77  			if k != "." {
    78  				list = append(list, k)
    79  			}
    80  		}
    81  		sort.Strings(list)
    82  		if len(list) > 15 {
    83  			list = append(list[:10], "...")
    84  		}
    85  		t.errorf("expected empty file system but found files:\n%s", strings.Join(list, "\n"))
    86  	}
    87  	for _, name := range expected {
    88  		if !found[name] {
    89  			t.errorf("expected but not found: %s", name)
    90  		}
    91  	}
    92  	if len(t.errText) == 0 {
    93  		return nil
    94  	}
    95  	return errors.New("TestFS found errors:\n" + string(t.errText))
    96  }
    97  
    98  // An fsTester holds state for running the test.
    99  type fsTester struct {
   100  	fsys    fs.FS
   101  	errText []byte
   102  	dirs    []string
   103  	files   []string
   104  }
   105  
   106  // errorf adds an error line to errText.
   107  func (t *fsTester) errorf(format string, args ...any) {
   108  	if len(t.errText) > 0 {
   109  		t.errText = append(t.errText, '\n')
   110  	}
   111  	t.errText = append(t.errText, fmt.Sprintf(format, args...)...)
   112  }
   113  
   114  func (t *fsTester) openDir(dir string) fs.ReadDirFile {
   115  	f, err := t.fsys.Open(dir)
   116  	if err != nil {
   117  		t.errorf("%s: Open: %v", dir, err)
   118  		return nil
   119  	}
   120  	d, ok := f.(fs.ReadDirFile)
   121  	if !ok {
   122  		f.Close()
   123  		t.errorf("%s: Open returned File type %T, not a fs.ReadDirFile", dir, f)
   124  		return nil
   125  	}
   126  	return d
   127  }
   128  
   129  // checkDir checks the directory dir, which is expected to exist
   130  // (it is either the root or was found in a directory listing with IsDir true).
   131  func (t *fsTester) checkDir(dir string) {
   132  	// Read entire directory.
   133  	t.dirs = append(t.dirs, dir)
   134  	d := t.openDir(dir)
   135  	if d == nil {
   136  		return
   137  	}
   138  	list, err := d.ReadDir(-1)
   139  	if err != nil {
   140  		d.Close()
   141  		t.errorf("%s: ReadDir(-1): %v", dir, err)
   142  		return
   143  	}
   144  
   145  	// Check all children.
   146  	var prefix string
   147  	if dir == "." {
   148  		prefix = ""
   149  	} else {
   150  		prefix = dir + "/"
   151  	}
   152  	for _, info := range list {
   153  		name := info.Name()
   154  		switch {
   155  		case name == ".", name == "..", name == "":
   156  			t.errorf("%s: ReadDir: child has invalid name: %#q", dir, name)
   157  			continue
   158  		case strings.Contains(name, "/"):
   159  			t.errorf("%s: ReadDir: child name contains slash: %#q", dir, name)
   160  			continue
   161  		case strings.Contains(name, `\`):
   162  			t.errorf("%s: ReadDir: child name contains backslash: %#q", dir, name)
   163  			continue
   164  		}
   165  		path := prefix + name
   166  		t.checkStat(path, info)
   167  		t.checkOpen(path)
   168  		if info.IsDir() {
   169  			t.checkDir(path)
   170  		} else {
   171  			t.checkFile(path)
   172  		}
   173  	}
   174  
   175  	// Check ReadDir(-1) at EOF.
   176  	list2, err := d.ReadDir(-1)
   177  	if len(list2) > 0 || err != nil {
   178  		d.Close()
   179  		t.errorf("%s: ReadDir(-1) at EOF = %d entries, %v, wanted 0 entries, nil", dir, len(list2), err)
   180  		return
   181  	}
   182  
   183  	// Check ReadDir(1) at EOF (different results).
   184  	list2, err = d.ReadDir(1)
   185  	if len(list2) > 0 || err != io.EOF {
   186  		d.Close()
   187  		t.errorf("%s: ReadDir(1) at EOF = %d entries, %v, wanted 0 entries, EOF", dir, len(list2), err)
   188  		return
   189  	}
   190  
   191  	// Check that close does not report an error.
   192  	if err := d.Close(); err != nil {
   193  		t.errorf("%s: Close: %v", dir, err)
   194  	}
   195  
   196  	// Check that closing twice doesn't crash.
   197  	// The return value doesn't matter.
   198  	d.Close()
   199  
   200  	// Reopen directory, read a second time, make sure contents match.
   201  	if d = t.openDir(dir); d == nil {
   202  		return
   203  	}
   204  	defer d.Close()
   205  	list2, err = d.ReadDir(-1)
   206  	if err != nil {
   207  		t.errorf("%s: second Open+ReadDir(-1): %v", dir, err)
   208  		return
   209  	}
   210  	t.checkDirList(dir, "first Open+ReadDir(-1) vs second Open+ReadDir(-1)", list, list2)
   211  
   212  	// Reopen directory, read a third time in pieces, make sure contents match.
   213  	if d = t.openDir(dir); d == nil {
   214  		return
   215  	}
   216  	defer d.Close()
   217  	list2 = nil
   218  	for {
   219  		n := 1
   220  		if len(list2) > 0 {
   221  			n = 2
   222  		}
   223  		frag, err := d.ReadDir(n)
   224  		if len(frag) > n {
   225  			t.errorf("%s: third Open: ReadDir(%d) after %d: %d entries (too many)", dir, n, len(list2), len(frag))
   226  			return
   227  		}
   228  		list2 = append(list2, frag...)
   229  		if err == io.EOF {
   230  			break
   231  		}
   232  		if err != nil {
   233  			t.errorf("%s: third Open: ReadDir(%d) after %d: %v", dir, n, len(list2), err)
   234  			return
   235  		}
   236  		if n == 0 {
   237  			t.errorf("%s: third Open: ReadDir(%d) after %d: 0 entries but nil error", dir, n, len(list2))
   238  			return
   239  		}
   240  	}
   241  	t.checkDirList(dir, "first Open+ReadDir(-1) vs third Open+ReadDir(1,2) loop", list, list2)
   242  
   243  	// If fsys has ReadDir, check that it matches and is sorted.
   244  	if fsys, ok := t.fsys.(fs.ReadDirFS); ok {
   245  		list2, err := fsys.ReadDir(dir)
   246  		if err != nil {
   247  			t.errorf("%s: fsys.ReadDir: %v", dir, err)
   248  			return
   249  		}
   250  		t.checkDirList(dir, "first Open+ReadDir(-1) vs fsys.ReadDir", list, list2)
   251  
   252  		for i := 0; i+1 < len(list2); i++ {
   253  			if list2[i].Name() >= list2[i+1].Name() {
   254  				t.errorf("%s: fsys.ReadDir: list not sorted: %s before %s", dir, list2[i].Name(), list2[i+1].Name())
   255  			}
   256  		}
   257  	}
   258  
   259  	// Check fs.ReadDir as well.
   260  	list2, err = fs.ReadDir(t.fsys, dir)
   261  	if err != nil {
   262  		t.errorf("%s: fs.ReadDir: %v", dir, err)
   263  		return
   264  	}
   265  	t.checkDirList(dir, "first Open+ReadDir(-1) vs fs.ReadDir", list, list2)
   266  
   267  	for i := 0; i+1 < len(list2); i++ {
   268  		if list2[i].Name() >= list2[i+1].Name() {
   269  			t.errorf("%s: fs.ReadDir: list not sorted: %s before %s", dir, list2[i].Name(), list2[i+1].Name())
   270  		}
   271  	}
   272  
   273  	t.checkGlob(dir, list2)
   274  }
   275  
   276  // formatEntry formats an fs.DirEntry into a string for error messages and comparison.
   277  func formatEntry(entry fs.DirEntry) string {
   278  	return fmt.Sprintf("%s IsDir=%v Type=%v", entry.Name(), entry.IsDir(), entry.Type())
   279  }
   280  
   281  // formatInfoEntry formats an fs.FileInfo into a string like the result of formatEntry, for error messages and comparison.
   282  func formatInfoEntry(info fs.FileInfo) string {
   283  	return fmt.Sprintf("%s IsDir=%v Type=%v", info.Name(), info.IsDir(), info.Mode().Type())
   284  }
   285  
   286  // formatInfo formats an fs.FileInfo into a string for error messages and comparison.
   287  func formatInfo(info fs.FileInfo) string {
   288  	return fmt.Sprintf("%s IsDir=%v Mode=%v Size=%d ModTime=%v", info.Name(), info.IsDir(), info.Mode(), info.Size(), info.ModTime())
   289  }
   290  
   291  // checkGlob checks that various glob patterns work if the file system implements GlobFS.
   292  func (t *fsTester) checkGlob(dir string, list []fs.DirEntry) {
   293  	if _, ok := t.fsys.(fs.GlobFS); !ok {
   294  		return
   295  	}
   296  
   297  	// Make a complex glob pattern prefix that only matches dir.
   298  	var glob string
   299  	if dir != "." {
   300  		elem := strings.Split(dir, "/")
   301  		for i, e := range elem {
   302  			var pattern []rune
   303  			for j, r := range e {
   304  				if r == '*' || r == '?' || r == '\\' || r == '[' || r == '-' {
   305  					pattern = append(pattern, '\\', r)
   306  					continue
   307  				}
   308  				switch (i + j) % 5 {
   309  				case 0:
   310  					pattern = append(pattern, r)
   311  				case 1:
   312  					pattern = append(pattern, '[', r, ']')
   313  				case 2:
   314  					pattern = append(pattern, '[', r, '-', r, ']')
   315  				case 3:
   316  					pattern = append(pattern, '[', '\\', r, ']')
   317  				case 4:
   318  					pattern = append(pattern, '[', '\\', r, '-', '\\', r, ']')
   319  				}
   320  			}
   321  			elem[i] = string(pattern)
   322  		}
   323  		glob = strings.Join(elem, "/") + "/"
   324  	}
   325  
   326  	// Test that malformed patterns are detected.
   327  	// The error is likely path.ErrBadPattern but need not be.
   328  	if _, err := t.fsys.(fs.GlobFS).Glob(glob + "nonexist/[]"); err == nil {
   329  		t.errorf("%s: Glob(%#q): bad pattern not detected", dir, glob+"nonexist/[]")
   330  	}
   331  
   332  	// Try to find a letter that appears in only some of the final names.
   333  	c := rune('a')
   334  	for ; c <= 'z'; c++ {
   335  		have, haveNot := false, false
   336  		for _, d := range list {
   337  			if strings.ContainsRune(d.Name(), c) {
   338  				have = true
   339  			} else {
   340  				haveNot = true
   341  			}
   342  		}
   343  		if have && haveNot {
   344  			break
   345  		}
   346  	}
   347  	if c > 'z' {
   348  		c = 'a'
   349  	}
   350  	glob += "*" + string(c) + "*"
   351  
   352  	var want []string
   353  	for _, d := range list {
   354  		if strings.ContainsRune(d.Name(), c) {
   355  			want = append(want, path.Join(dir, d.Name()))
   356  		}
   357  	}
   358  
   359  	names, err := t.fsys.(fs.GlobFS).Glob(glob)
   360  	if err != nil {
   361  		t.errorf("%s: Glob(%#q): %v", dir, glob, err)
   362  		return
   363  	}
   364  	if reflect.DeepEqual(want, names) {
   365  		return
   366  	}
   367  
   368  	if !sort.StringsAreSorted(names) {
   369  		t.errorf("%s: Glob(%#q): unsorted output:\n%s", dir, glob, strings.Join(names, "\n"))
   370  		sort.Strings(names)
   371  	}
   372  
   373  	var problems []string
   374  	for len(want) > 0 || len(names) > 0 {
   375  		switch {
   376  		case len(want) > 0 && len(names) > 0 && want[0] == names[0]:
   377  			want, names = want[1:], names[1:]
   378  		case len(want) > 0 && (len(names) == 0 || want[0] < names[0]):
   379  			problems = append(problems, "missing: "+want[0])
   380  			want = want[1:]
   381  		default:
   382  			problems = append(problems, "extra: "+names[0])
   383  			names = names[1:]
   384  		}
   385  	}
   386  	t.errorf("%s: Glob(%#q): wrong output:\n%s", dir, glob, strings.Join(problems, "\n"))
   387  }
   388  
   389  // checkStat checks that a direct stat of path matches entry,
   390  // which was found in the parent's directory listing.
   391  func (t *fsTester) checkStat(path string, entry fs.DirEntry) {
   392  	file, err := t.fsys.Open(path)
   393  	if err != nil {
   394  		t.errorf("%s: Open: %v", path, err)
   395  		return
   396  	}
   397  	info, err := file.Stat()
   398  	file.Close()
   399  	if err != nil {
   400  		t.errorf("%s: Stat: %v", path, err)
   401  		return
   402  	}
   403  	fentry := formatEntry(entry)
   404  	fientry := formatInfoEntry(info)
   405  	// Note: mismatch here is OK for symlink, because Open dereferences symlink.
   406  	if fentry != fientry && entry.Type()&fs.ModeSymlink == 0 {
   407  		t.errorf("%s: mismatch:\n\tentry = %s\n\tfile.Stat() = %s", path, fentry, fientry)
   408  	}
   409  
   410  	einfo, err := entry.Info()
   411  	if err != nil {
   412  		t.errorf("%s: entry.Info: %v", path, err)
   413  		return
   414  	}
   415  	finfo := formatInfo(info)
   416  	if entry.Type()&fs.ModeSymlink != 0 {
   417  		// For symlink, just check that entry.Info matches entry on common fields.
   418  		// Open deferences symlink, so info itself may differ.
   419  		feentry := formatInfoEntry(einfo)
   420  		if fentry != feentry {
   421  			t.errorf("%s: mismatch\n\tentry = %s\n\tentry.Info() = %s\n", path, fentry, feentry)
   422  		}
   423  	} else {
   424  		feinfo := formatInfo(einfo)
   425  		if feinfo != finfo {
   426  			t.errorf("%s: mismatch:\n\tentry.Info() = %s\n\tfile.Stat() = %s\n", path, feinfo, finfo)
   427  		}
   428  	}
   429  
   430  	// Stat should be the same as Open+Stat, even for symlinks.
   431  	info2, err := fs.Stat(t.fsys, path)
   432  	if err != nil {
   433  		t.errorf("%s: fs.Stat: %v", path, err)
   434  		return
   435  	}
   436  	finfo2 := formatInfo(info2)
   437  	if finfo2 != finfo {
   438  		t.errorf("%s: fs.Stat(...) = %s\n\twant %s", path, finfo2, finfo)
   439  	}
   440  
   441  	if fsys, ok := t.fsys.(fs.StatFS); ok {
   442  		info2, err := fsys.Stat(path)
   443  		if err != nil {
   444  			t.errorf("%s: fsys.Stat: %v", path, err)
   445  			return
   446  		}
   447  		finfo2 := formatInfo(info2)
   448  		if finfo2 != finfo {
   449  			t.errorf("%s: fsys.Stat(...) = %s\n\twant %s", path, finfo2, finfo)
   450  		}
   451  	}
   452  }
   453  
   454  // checkDirList checks that two directory lists contain the same files and file info.
   455  // The order of the lists need not match.
   456  func (t *fsTester) checkDirList(dir, desc string, list1, list2 []fs.DirEntry) {
   457  	old := make(map[string]fs.DirEntry)
   458  	checkMode := func(entry fs.DirEntry) {
   459  		if entry.IsDir() != (entry.Type()&fs.ModeDir != 0) {
   460  			if entry.IsDir() {
   461  				t.errorf("%s: ReadDir returned %s with IsDir() = true, Type() & ModeDir = 0", dir, entry.Name())
   462  			} else {
   463  				t.errorf("%s: ReadDir returned %s with IsDir() = false, Type() & ModeDir = ModeDir", dir, entry.Name())
   464  			}
   465  		}
   466  	}
   467  
   468  	for _, entry1 := range list1 {
   469  		old[entry1.Name()] = entry1
   470  		checkMode(entry1)
   471  	}
   472  
   473  	var diffs []string
   474  	for _, entry2 := range list2 {
   475  		entry1 := old[entry2.Name()]
   476  		if entry1 == nil {
   477  			checkMode(entry2)
   478  			diffs = append(diffs, "+ "+formatEntry(entry2))
   479  			continue
   480  		}
   481  		if formatEntry(entry1) != formatEntry(entry2) {
   482  			diffs = append(diffs, "- "+formatEntry(entry1), "+ "+formatEntry(entry2))
   483  		}
   484  		delete(old, entry2.Name())
   485  	}
   486  	for _, entry1 := range old {
   487  		diffs = append(diffs, "- "+formatEntry(entry1))
   488  	}
   489  
   490  	if len(diffs) == 0 {
   491  		return
   492  	}
   493  
   494  	sort.Slice(diffs, func(i, j int) bool {
   495  		fi := strings.Fields(diffs[i])
   496  		fj := strings.Fields(diffs[j])
   497  		// sort by name (i < j) and then +/- (j < i, because + < -)
   498  		return fi[1]+" "+fj[0] < fj[1]+" "+fi[0]
   499  	})
   500  
   501  	t.errorf("%s: diff %s:\n\t%s", dir, desc, strings.Join(diffs, "\n\t"))
   502  }
   503  
   504  // checkFile checks that basic file reading works correctly.
   505  func (t *fsTester) checkFile(file string) {
   506  	t.files = append(t.files, file)
   507  
   508  	// Read entire file.
   509  	f, err := t.fsys.Open(file)
   510  	if err != nil {
   511  		t.errorf("%s: Open: %v", file, err)
   512  		return
   513  	}
   514  
   515  	data, err := io.ReadAll(f)
   516  	if err != nil {
   517  		f.Close()
   518  		t.errorf("%s: Open+ReadAll: %v", file, err)
   519  		return
   520  	}
   521  
   522  	if err := f.Close(); err != nil {
   523  		t.errorf("%s: Close: %v", file, err)
   524  	}
   525  
   526  	// Check that closing twice doesn't crash.
   527  	// The return value doesn't matter.
   528  	f.Close()
   529  
   530  	// Check that ReadFile works if present.
   531  	if fsys, ok := t.fsys.(fs.ReadFileFS); ok {
   532  		data2, err := fsys.ReadFile(file)
   533  		if err != nil {
   534  			t.errorf("%s: fsys.ReadFile: %v", file, err)
   535  			return
   536  		}
   537  		t.checkFileRead(file, "ReadAll vs fsys.ReadFile", data, data2)
   538  
   539  		// Modify the data and check it again. Modifying the
   540  		// returned byte slice should not affect the next call.
   541  		for i := range data2 {
   542  			data2[i]++
   543  		}
   544  		data2, err = fsys.ReadFile(file)
   545  		if err != nil {
   546  			t.errorf("%s: second call to fsys.ReadFile: %v", file, err)
   547  			return
   548  		}
   549  		t.checkFileRead(file, "Readall vs second fsys.ReadFile", data, data2)
   550  
   551  		t.checkBadPath(file, "ReadFile",
   552  			func(name string) error { _, err := fsys.ReadFile(name); return err })
   553  	}
   554  
   555  	// Check that fs.ReadFile works with t.fsys.
   556  	data2, err := fs.ReadFile(t.fsys, file)
   557  	if err != nil {
   558  		t.errorf("%s: fs.ReadFile: %v", file, err)
   559  		return
   560  	}
   561  	t.checkFileRead(file, "ReadAll vs fs.ReadFile", data, data2)
   562  
   563  	// Use iotest.TestReader to check small reads, Seek, ReadAt.
   564  	f, err = t.fsys.Open(file)
   565  	if err != nil {
   566  		t.errorf("%s: second Open: %v", file, err)
   567  		return
   568  	}
   569  	defer f.Close()
   570  	if err := iotest.TestReader(f, data); err != nil {
   571  		t.errorf("%s: failed TestReader:\n\t%s", file, strings.ReplaceAll(err.Error(), "\n", "\n\t"))
   572  	}
   573  }
   574  
   575  func (t *fsTester) checkFileRead(file, desc string, data1, data2 []byte) {
   576  	if string(data1) != string(data2) {
   577  		t.errorf("%s: %s: different data returned\n\t%q\n\t%q", file, desc, data1, data2)
   578  		return
   579  	}
   580  }
   581  
   582  // checkBadPath checks that various invalid forms of file's name cannot be opened using t.fsys.Open.
   583  func (t *fsTester) checkOpen(file string) {
   584  	t.checkBadPath(file, "Open", func(file string) error {
   585  		f, err := t.fsys.Open(file)
   586  		if err == nil {
   587  			f.Close()
   588  		}
   589  		return err
   590  	})
   591  }
   592  
   593  // checkBadPath checks that various invalid forms of file's name cannot be opened using open.
   594  func (t *fsTester) checkBadPath(file string, desc string, open func(string) error) {
   595  	bad := []string{
   596  		"/" + file,
   597  		file + "/.",
   598  	}
   599  	if file == "." {
   600  		bad = append(bad, "/")
   601  	}
   602  	if i := strings.Index(file, "/"); i >= 0 {
   603  		bad = append(bad,
   604  			file[:i]+"//"+file[i+1:],
   605  			file[:i]+"/./"+file[i+1:],
   606  			file[:i]+`\`+file[i+1:],
   607  			file[:i]+"/../"+file,
   608  		)
   609  	}
   610  	if i := strings.LastIndex(file, "/"); i >= 0 {
   611  		bad = append(bad,
   612  			file[:i]+"//"+file[i+1:],
   613  			file[:i]+"/./"+file[i+1:],
   614  			file[:i]+`\`+file[i+1:],
   615  			file+"/../"+file[i+1:],
   616  		)
   617  	}
   618  
   619  	for _, b := range bad {
   620  		if err := open(b); err == nil {
   621  			t.errorf("%s: %s(%s) succeeded, want error", file, desc, b)
   622  		}
   623  	}
   624  }
   625
View as plain text