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  //
    37  func TestFS(fsys fs.FS, expected ...string) error {
    38  	if err := testFS(fsys, expected...); err != nil {
    39  		return err
    40  	}
    41  	for _, name := range expected {
    42  		if i := strings.Index(name, "/"); i >= 0 {
    43  			dir, dirSlash := name[:i], name[:i+1]
    44  			var subExpected []string
    45  			for _, name := range expected {
    46  				if strings.HasPrefix(name, dirSlash) {
    47  					subExpected = append(subExpected, name[len(dirSlash):])
    48  				}
    49  			}
    50  			sub, err := fs.Sub(fsys, dir)
    51  			if err != nil {
    52  				return err
    53  			}
    54  			if err := testFS(sub, subExpected...); err != nil {
    55  				return fmt.Errorf("testing fs.Sub(fsys, %s): %v", dir, err)
    56  			}
    57  			break // one sub-test is enough
    58  		}
    59  	}
    60  	return nil
    61  }
    62  
    63  func testFS(fsys fs.FS, expected ...string) error {
    64  	t := fsTester{fsys: fsys}
    65  	t.checkDir(".")
    66  	t.checkOpen(".")
    67  	found := make(map[string]bool)
    68  	for _, dir := range t.dirs {
    69  		found[dir] = true
    70  	}
    71  	for _, file := range t.files {
    72  		found[file] = true
    73  	}
    74  	delete(found, ".")
    75  	if len(expected) == 0 && len(found) > 0 {
    76  		var list []string
    77  		for k := range found {
    78  			if k != "." {
    79  				list = append(list, k)
    80  			}
    81  		}
    82  		sort.Strings(list)
    83  		if len(list) > 15 {
    84  			list = append(list[:10], "...")
    85  		}
    86  		t.errorf("expected empty file system but found files:\n%s", strings.Join(list, "\n"))
    87  	}
    88  	for _, name := range expected {
    89  		if !found[name] {
    90  			t.errorf("expected but not found: %s", name)
    91  		}
    92  	}
    93  	if len(t.errText) == 0 {
    94  		return nil
    95  	}
    96  	return errors.New("TestFS found errors:\n" + string(t.errText))
    97  }
    98  
    99  // An fsTester holds state for running the test.
   100  type fsTester struct {
   101  	fsys    fs.FS
   102  	errText []byte
   103  	dirs    []string
   104  	files   []string
   105  }
   106  
   107  // errorf adds an error line to errText.
   108  func (t *fsTester) errorf(format string, args ...interface{}) {
   109  	if len(t.errText) > 0 {
   110  		t.errText = append(t.errText, '\n')
   111  	}
   112  	t.errText = append(t.errText, fmt.Sprintf(format, args...)...)
   113  }
   114  
   115  func (t *fsTester) openDir(dir string) fs.ReadDirFile {
   116  	f, err := t.fsys.Open(dir)
   117  	if err != nil {
   118  		t.errorf("%s: Open: %v", dir, err)
   119  		return nil
   120  	}
   121  	d, ok := f.(fs.ReadDirFile)
   122  	if !ok {
   123  		f.Close()
   124  		t.errorf("%s: Open returned File type %T, not a fs.ReadDirFile", dir, f)
   125  		return nil
   126  	}
   127  	return d
   128  }
   129  
   130  // checkDir checks the directory dir, which is expected to exist
   131  // (it is either the root or was found in a directory listing with IsDir true).
   132  func (t *fsTester) checkDir(dir string) {
   133  	// Read entire directory.
   134  	t.dirs = append(t.dirs, dir)
   135  	d := t.openDir(dir)
   136  	if d == nil {
   137  		return
   138  	}
   139  	list, err := d.ReadDir(-1)
   140  	if err != nil {
   141  		d.Close()
   142  		t.errorf("%s: ReadDir(-1): %v", dir, err)
   143  		return
   144  	}
   145  
   146  	// Check all children.
   147  	var prefix string
   148  	if dir == "." {
   149  		prefix = ""
   150  	} else {
   151  		prefix = dir + "/"
   152  	}
   153  	for _, info := range list {
   154  		name := info.Name()
   155  		switch {
   156  		case name == ".", name == "..", name == "":
   157  			t.errorf("%s: ReadDir: child has invalid name: %#q", dir, name)
   158  			continue
   159  		case strings.Contains(name, "/"):
   160  			t.errorf("%s: ReadDir: child name contains slash: %#q", dir, name)
   161  			continue
   162  		case strings.Contains(name, `\`):
   163  			t.errorf("%s: ReadDir: child name contains backslash: %#q", dir, name)
   164  			continue
   165  		}
   166  		path := prefix + name
   167  		t.checkStat(path, info)
   168  		t.checkOpen(path)
   169  		if info.IsDir() {
   170  			t.checkDir(path)
   171  		} else {
   172  			t.checkFile(path)
   173  		}
   174  	}
   175  
   176  	// Check ReadDir(-1) at EOF.
   177  	list2, err := d.ReadDir(-1)
   178  	if len(list2) > 0 || err != nil {
   179  		d.Close()
   180  		t.errorf("%s: ReadDir(-1) at EOF = %d entries, %v, wanted 0 entries, nil", dir, len(list2), err)
   181  		return
   182  	}
   183  
   184  	// Check ReadDir(1) at EOF (different results).
   185  	list2, err = d.ReadDir(1)
   186  	if len(list2) > 0 || err != io.EOF {
   187  		d.Close()
   188  		t.errorf("%s: ReadDir(1) at EOF = %d entries, %v, wanted 0 entries, EOF", dir, len(list2), err)
   189  		return
   190  	}
   191  
   192  	// Check that close does not report an error.
   193  	if err := d.Close(); err != nil {
   194  		t.errorf("%s: Close: %v", dir, err)
   195  	}
   196  
   197  	// Check that closing twice doesn't crash.
   198  	// The return value doesn't matter.
   199  	d.Close()
   200  
   201  	// Reopen directory, read a second time, make sure contents match.
   202  	if d = t.openDir(dir); d == nil {
   203  		return
   204  	}
   205  	defer d.Close()
   206  	list2, err = d.ReadDir(-1)
   207  	if err != nil {
   208  		t.errorf("%s: second Open+ReadDir(-1): %v", dir, err)
   209  		return
   210  	}
   211  	t.checkDirList(dir, "first Open+ReadDir(-1) vs second Open+ReadDir(-1)", list, list2)
   212  
   213  	// Reopen directory, read a third time in pieces, make sure contents match.
   214  	if d = t.openDir(dir); d == nil {
   215  		return
   216  	}
   217  	defer d.Close()
   218  	list2 = nil
   219  	for {
   220  		n := 1
   221  		if len(list2) > 0 {
   222  			n = 2
   223  		}
   224  		frag, err := d.ReadDir(n)
   225  		if len(frag) > n {
   226  			t.errorf("%s: third Open: ReadDir(%d) after %d: %d entries (too many)", dir, n, len(list2), len(frag))
   227  			return
   228  		}
   229  		list2 = append(list2, frag...)
   230  		if err == io.EOF {
   231  			break
   232  		}
   233  		if err != nil {
   234  			t.errorf("%s: third Open: ReadDir(%d) after %d: %v", dir, n, len(list2), err)
   235  			return
   236  		}
   237  		if n == 0 {
   238  			t.errorf("%s: third Open: ReadDir(%d) after %d: 0 entries but nil error", dir, n, len(list2))
   239  			return
   240  		}
   241  	}
   242  	t.checkDirList(dir, "first Open+ReadDir(-1) vs third Open+ReadDir(1,2) loop", list, list2)
   243  
   244  	// If fsys has ReadDir, check that it matches and is sorted.
   245  	if fsys, ok := t.fsys.(fs.ReadDirFS); ok {
   246  		list2, err := fsys.ReadDir(dir)
   247  		if err != nil {
   248  			t.errorf("%s: fsys.ReadDir: %v", dir, err)
   249  			return
   250  		}
   251  		t.checkDirList(dir, "first Open+ReadDir(-1) vs fsys.ReadDir", list, list2)
   252  
   253  		for i := 0; i+1 < len(list2); i++ {
   254  			if list2[i].Name() >= list2[i+1].Name() {
   255  				t.errorf("%s: fsys.ReadDir: list not sorted: %s before %s", dir, list2[i].Name(), list2[i+1].Name())
   256  			}
   257  		}
   258  	}
   259  
   260  	// Check fs.ReadDir as well.
   261  	list2, err = fs.ReadDir(t.fsys, dir)
   262  	if err != nil {
   263  		t.errorf("%s: fs.ReadDir: %v", dir, err)
   264  		return
   265  	}
   266  	t.checkDirList(dir, "first Open+ReadDir(-1) vs fs.ReadDir", list, list2)
   267  
   268  	for i := 0; i+1 < len(list2); i++ {
   269  		if list2[i].Name() >= list2[i+1].Name() {
   270  			t.errorf("%s: fs.ReadDir: list not sorted: %s before %s", dir, list2[i].Name(), list2[i+1].Name())
   271  		}
   272  	}
   273  
   274  	t.checkGlob(dir, list)
   275  }
   276  
   277  // formatEntry formats an fs.DirEntry into a string for error messages and comparison.
   278  func formatEntry(entry fs.DirEntry) string {
   279  	return fmt.Sprintf("%s IsDir=%v Type=%v", entry.Name(), entry.IsDir(), entry.Type())
   280  }
   281  
   282  // formatInfoEntry formats an fs.FileInfo into a string like the result of formatEntry, for error messages and comparison.
   283  func formatInfoEntry(info fs.FileInfo) string {
   284  	return fmt.Sprintf("%s IsDir=%v Type=%v", info.Name(), info.IsDir(), info.Mode().Type())
   285  }
   286  
   287  // formatInfo formats an fs.FileInfo into a string for error messages and comparison.
   288  func formatInfo(info fs.FileInfo) string {
   289  	return fmt.Sprintf("%s IsDir=%v Mode=%v Size=%d ModTime=%v", info.Name(), info.IsDir(), info.Mode(), info.Size(), info.ModTime())
   290  }
   291  
   292  // checkGlob checks that various glob patterns work if the file system implements GlobFS.
   293  func (t *fsTester) checkGlob(dir string, list []fs.DirEntry) {
   294  	if _, ok := t.fsys.(fs.GlobFS); !ok {
   295  		return
   296  	}
   297  
   298  	// Make a complex glob pattern prefix that only matches dir.
   299  	var glob string
   300  	if dir != "." {
   301  		elem := strings.Split(dir, "/")
   302  		for i, e := range elem {
   303  			var pattern []rune
   304  			for j, r := range e {
   305  				if r == '*' || r == '?' || r == '\\' || r == '[' || r == '-' {
   306  					pattern = append(pattern, '\\', r)
   307  					continue
   308  				}
   309  				switch (i + j) % 5 {
   310  				case 0:
   311  					pattern = append(pattern, r)
   312  				case 1:
   313  					pattern = append(pattern, '[', r, ']')
   314  				case 2:
   315  					pattern = append(pattern, '[', r, '-', r, ']')
   316  				case 3:
   317  					pattern = append(pattern, '[', '\\', r, ']')
   318  				case 4:
   319  					pattern = append(pattern, '[', '\\', r, '-', '\\', r, ']')
   320  				}
   321  			}
   322  			elem[i] = string(pattern)
   323  		}
   324  		glob = strings.Join(elem, "/") + "/"
   325  	}
   326  
   327  	// Test that malformed patterns are detected.
   328  	// The error is likely path.ErrBadPattern but need not be.
   329  	if _, err := t.fsys.(fs.GlobFS).Glob(glob + "nonexist/[]"); err == nil {
   330  		t.errorf("%s: Glob(%#q): bad pattern not detected", dir, glob+"nonexist/[]")
   331  	}
   332  
   333  	// Try to find a letter that appears in only some of the final names.
   334  	c := rune('a')
   335  	for ; c <= 'z'; c++ {
   336  		have, haveNot := false, false
   337  		for _, d := range list {
   338  			if strings.ContainsRune(d.Name(), c) {
   339  				have = true
   340  			} else {
   341  				haveNot = true
   342  			}
   343  		}
   344  		if have && haveNot {
   345  			break
   346  		}
   347  	}
   348  	if c > 'z' {
   349  		c = 'a'
   350  	}
   351  	glob += "*" + string(c) + "*"
   352  
   353  	var want []string
   354  	for _, d := range list {
   355  		if strings.ContainsRune(d.Name(), c) {
   356  			want = append(want, path.Join(dir, d.Name()))
   357  		}
   358  	}
   359  
   360  	names, err := t.fsys.(fs.GlobFS).Glob(glob)
   361  	if err != nil {
   362  		t.errorf("%s: Glob(%#q): %v", dir, glob, err)
   363  		return
   364  	}
   365  	if reflect.DeepEqual(want, names) {
   366  		return
   367  	}
   368  
   369  	if !sort.StringsAreSorted(names) {
   370  		t.errorf("%s: Glob(%#q): unsorted output:\n%s", dir, glob, strings.Join(names, "\n"))
   371  		sort.Strings(names)
   372  	}
   373  
   374  	var problems []string
   375  	for len(want) > 0 || len(names) > 0 {
   376  		switch {
   377  		case len(want) > 0 && len(names) > 0 && want[0] == names[0]:
   378  			want, names = want[1:], names[1:]
   379  		case len(want) > 0 && (len(names) == 0 || want[0] < names[0]):
   380  			problems = append(problems, "missing: "+want[0])
   381  			want = want[1:]
   382  		default:
   383  			problems = append(problems, "extra: "+names[0])
   384  			names = names[1:]
   385  		}
   386  	}
   387  	t.errorf("%s: Glob(%#q): wrong output:\n%s", dir, glob, strings.Join(problems, "\n"))
   388  }
   389  
   390  // checkStat checks that a direct stat of path matches entry,
   391  // which was found in the parent's directory listing.
   392  func (t *fsTester) checkStat(path string, entry fs.DirEntry) {
   393  	file, err := t.fsys.Open(path)
   394  	if err != nil {
   395  		t.errorf("%s: Open: %v", path, err)
   396  		return
   397  	}
   398  	info, err := file.Stat()
   399  	file.Close()
   400  	if err != nil {
   401  		t.errorf("%s: Stat: %v", path, err)
   402  		return
   403  	}
   404  	fentry := formatEntry(entry)
   405  	fientry := formatInfoEntry(info)
   406  	// Note: mismatch here is OK for symlink, because Open dereferences symlink.
   407  	if fentry != fientry && entry.Type()&fs.ModeSymlink == 0 {
   408  		t.errorf("%s: mismatch:\n\tentry = %s\n\tfile.Stat() = %s", path, fentry, fientry)
   409  	}
   410  
   411  	einfo, err := entry.Info()
   412  	if err != nil {
   413  		t.errorf("%s: entry.Info: %v", path, err)
   414  		return
   415  	}
   416  	finfo := formatInfo(info)
   417  	if entry.Type()&fs.ModeSymlink != 0 {
   418  		// For symlink, just check that entry.Info matches entry on common fields.
   419  		// Open deferences symlink, so info itself may differ.
   420  		feentry := formatInfoEntry(einfo)
   421  		if fentry != feentry {
   422  			t.errorf("%s: mismatch\n\tentry = %s\n\tentry.Info() = %s\n", path, fentry, feentry)
   423  		}
   424  	} else {
   425  		feinfo := formatInfo(einfo)
   426  		if feinfo != finfo {
   427  			t.errorf("%s: mismatch:\n\tentry.Info() = %s\n\tfile.Stat() = %s\n", path, feinfo, finfo)
   428  		}
   429  	}
   430  
   431  	// Stat should be the same as Open+Stat, even for symlinks.
   432  	info2, err := fs.Stat(t.fsys, path)
   433  	if err != nil {
   434  		t.errorf("%s: fs.Stat: %v", path, err)
   435  		return
   436  	}
   437  	finfo2 := formatInfo(info2)
   438  	if finfo2 != finfo {
   439  		t.errorf("%s: fs.Stat(...) = %s\n\twant %s", path, finfo2, finfo)
   440  	}
   441  
   442  	if fsys, ok := t.fsys.(fs.StatFS); ok {
   443  		info2, err := fsys.Stat(path)
   444  		if err != nil {
   445  			t.errorf("%s: fsys.Stat: %v", path, err)
   446  			return
   447  		}
   448  		finfo2 := formatInfo(info2)
   449  		if finfo2 != finfo {
   450  			t.errorf("%s: fsys.Stat(...) = %s\n\twant %s", path, finfo2, finfo)
   451  		}
   452  	}
   453  }
   454  
   455  // checkDirList checks that two directory lists contain the same files and file info.
   456  // The order of the lists need not match.
   457  func (t *fsTester) checkDirList(dir, desc string, list1, list2 []fs.DirEntry) {
   458  	old := make(map[string]fs.DirEntry)
   459  	checkMode := func(entry fs.DirEntry) {
   460  		if entry.IsDir() != (entry.Type()&fs.ModeDir != 0) {
   461  			if entry.IsDir() {
   462  				t.errorf("%s: ReadDir returned %s with IsDir() = true, Type() & ModeDir = 0", dir, entry.Name())
   463  			} else {
   464  				t.errorf("%s: ReadDir returned %s with IsDir() = false, Type() & ModeDir = ModeDir", dir, entry.Name())
   465  			}
   466  		}
   467  	}
   468  
   469  	for _, entry1 := range list1 {
   470  		old[entry1.Name()] = entry1
   471  		checkMode(entry1)
   472  	}
   473  
   474  	var diffs []string
   475  	for _, entry2 := range list2 {
   476  		entry1 := old[entry2.Name()]
   477  		if entry1 == nil {
   478  			checkMode(entry2)
   479  			diffs = append(diffs, "+ "+formatEntry(entry2))
   480  			continue
   481  		}
   482  		if formatEntry(entry1) != formatEntry(entry2) {
   483  			diffs = append(diffs, "- "+formatEntry(entry1), "+ "+formatEntry(entry2))
   484  		}
   485  		delete(old, entry2.Name())
   486  	}
   487  	for _, entry1 := range old {
   488  		diffs = append(diffs, "- "+formatEntry(entry1))
   489  	}
   490  
   491  	if len(diffs) == 0 {
   492  		return
   493  	}
   494  
   495  	sort.Slice(diffs, func(i, j int) bool {
   496  		fi := strings.Fields(diffs[i])
   497  		fj := strings.Fields(diffs[j])
   498  		// sort by name (i < j) and then +/- (j < i, because + < -)
   499  		return fi[1]+" "+fj[0] < fj[1]+" "+fi[0]
   500  	})
   501  
   502  	t.errorf("%s: diff %s:\n\t%s", dir, desc, strings.Join(diffs, "\n\t"))
   503  }
   504  
   505  // checkFile checks that basic file reading works correctly.
   506  func (t *fsTester) checkFile(file string) {
   507  	t.files = append(t.files, file)
   508  
   509  	// Read entire file.
   510  	f, err := t.fsys.Open(file)
   511  	if err != nil {
   512  		t.errorf("%s: Open: %v", file, err)
   513  		return
   514  	}
   515  
   516  	data, err := io.ReadAll(f)
   517  	if err != nil {
   518  		f.Close()
   519  		t.errorf("%s: Open+ReadAll: %v", file, err)
   520  		return
   521  	}
   522  
   523  	if err := f.Close(); err != nil {
   524  		t.errorf("%s: Close: %v", file, err)
   525  	}
   526  
   527  	// Check that closing twice doesn't crash.
   528  	// The return value doesn't matter.
   529  	f.Close()
   530  
   531  	// Check that ReadFile works if present.
   532  	if fsys, ok := t.fsys.(fs.ReadFileFS); ok {
   533  		data2, err := fsys.ReadFile(file)
   534  		if err != nil {
   535  			t.errorf("%s: fsys.ReadFile: %v", file, err)
   536  			return
   537  		}
   538  		t.checkFileRead(file, "ReadAll vs fsys.ReadFile", data, data2)
   539  
   540  		// Modify the data and check it again. Modifying the
   541  		// returned byte slice should not affect the next call.
   542  		for i := range data2 {
   543  			data2[i]++
   544  		}
   545  		data2, err = fsys.ReadFile(file)
   546  		if err != nil {
   547  			t.errorf("%s: second call to fsys.ReadFile: %v", file, err)
   548  			return
   549  		}
   550  		t.checkFileRead(file, "Readall vs second fsys.ReadFile", data, data2)
   551  
   552  		t.checkBadPath(file, "ReadFile",
   553  			func(name string) error { _, err := fsys.ReadFile(name); return err })
   554  	}
   555  
   556  	// Check that fs.ReadFile works with t.fsys.
   557  	data2, err := fs.ReadFile(t.fsys, file)
   558  	if err != nil {
   559  		t.errorf("%s: fs.ReadFile: %v", file, err)
   560  		return
   561  	}
   562  	t.checkFileRead(file, "ReadAll vs fs.ReadFile", data, data2)
   563  
   564  	// Use iotest.TestReader to check small reads, Seek, ReadAt.
   565  	f, err = t.fsys.Open(file)
   566  	if err != nil {
   567  		t.errorf("%s: second Open: %v", file, err)
   568  		return
   569  	}
   570  	defer f.Close()
   571  	if err := iotest.TestReader(f, data); err != nil {
   572  		t.errorf("%s: failed TestReader:\n\t%s", file, strings.ReplaceAll(err.Error(), "\n", "\n\t"))
   573  	}
   574  }
   575  
   576  func (t *fsTester) checkFileRead(file, desc string, data1, data2 []byte) {
   577  	if string(data1) != string(data2) {
   578  		t.errorf("%s: %s: different data returned\n\t%q\n\t%q", file, desc, data1, data2)
   579  		return
   580  	}
   581  }
   582  
   583  // checkBadPath checks that various invalid forms of file's name cannot be opened using t.fsys.Open.
   584  func (t *fsTester) checkOpen(file string) {
   585  	t.checkBadPath(file, "Open", func(file string) error {
   586  		f, err := t.fsys.Open(file)
   587  		if err == nil {
   588  			f.Close()
   589  		}
   590  		return err
   591  	})
   592  }
   593  
   594  // checkBadPath checks that various invalid forms of file's name cannot be opened using open.
   595  func (t *fsTester) checkBadPath(file string, desc string, open func(string) error) {
   596  	bad := []string{
   597  		"/" + file,
   598  		file + "/.",
   599  	}
   600  	if file == "." {
   601  		bad = append(bad, "/")
   602  	}
   603  	if i := strings.Index(file, "/"); i >= 0 {
   604  		bad = append(bad,
   605  			file[:i]+"//"+file[i+1:],
   606  			file[:i]+"/./"+file[i+1:],
   607  			file[:i]+`\`+file[i+1:],
   608  			file[:i]+"/../"+file,
   609  		)
   610  	}
   611  	if i := strings.LastIndex(file, "/"); i >= 0 {
   612  		bad = append(bad,
   613  			file[:i]+"//"+file[i+1:],
   614  			file[:i]+"/./"+file[i+1:],
   615  			file[:i]+`\`+file[i+1:],
   616  			file+"/../"+file[i+1:],
   617  		)
   618  	}
   619  
   620  	for _, b := range bad {
   621  		if err := open(b); err == nil {
   622  			t.errorf("%s: %s(%s) succeeded, want error", file, desc, b)
   623  		}
   624  	}
   625  }
   626
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