testing/fstest: avoid symlink-induced failures in tester

Do not require directory entry and Stat result to match for symlinks,
because they won't (Stat dereferences the symlink).

Fixes #44113.

Change-Id: Ifc6dbce5719906e2f42254a7172f1ef787464a9e
Reviewed-on: https://go-review.googlesource.com/c/go/+/290009
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

diff --git a/src/testing/fstest/testfs.go b/src/testing/fstest/testfs.go
index a7f8007333e310eef526c61e667b789b2f125301..8fc8acaaf3bf1bb88fda7138002f5678a8266178 100644 (file)
--- a/src/testing/fstest/testfs.go
+++ b/src/testing/fstest/testfs.go
@@ -403,9 +403,10 @@ func (t *fsTester) checkStat(path string, entry fs.DirEntry) {
                return
        }
        fentry := formatEntry(entry)
-       finfo := formatInfoEntry(info)
-       if fentry != finfo {
-               t.errorf("%s: mismatch:\n\tentry = %s\n\tfile.Stat() = %s", path, fentry, finfo)
+       fientry := formatInfoEntry(info)
+       // Note: mismatch here is OK for symlink, because Open dereferences symlink.
+       if fentry != fientry && entry.Type()&fs.ModeSymlink == 0 {
+               t.errorf("%s: mismatch:\n\tentry = %s\n\tfile.Stat() = %s", path, fentry, fientry)
        }
 
        einfo, err := entry.Info()
@@ -413,12 +414,22 @@ func (t *fsTester) checkStat(path string, entry fs.DirEntry) {
                t.errorf("%s: entry.Info: %v", path, err)
                return
        }
-       fentry = formatInfo(einfo)
-       finfo = formatInfo(info)
-       if fentry != finfo {
-               t.errorf("%s: mismatch:\n\tentry.Info() = %s\n\tfile.Stat() = %s\n", path, fentry, finfo)
+       finfo := formatInfo(info)
+       if entry.Type()&fs.ModeSymlink != 0 {
+               // For symlink, just check that entry.Info matches entry on common fields.
+               // Open deferences symlink, so info itself may differ.
+               feentry := formatInfoEntry(einfo)
+               if fentry != feentry {
+                       t.errorf("%s: mismatch\n\tentry = %s\n\tentry.Info() = %s\n", path, fentry, feentry)
+               }
+       } else {
+               feinfo := formatInfo(einfo)
+               if feinfo != finfo {
+                       t.errorf("%s: mismatch:\n\tentry.Info() = %s\n\tfile.Stat() = %s\n", path, feinfo, finfo)
+               }
        }
 
+       // Stat should be the same as Open+Stat, even for symlinks.
        info2, err := fs.Stat(t.fsys, path)
        if err != nil {
                t.errorf("%s: fs.Stat: %v", path, err)

diff --git a/src/testing/fstest/testfs_test.go b/src/testing/fstest/testfs_test.go
new file mode 100644 (file)
index 0000000..5b8813c
--- /dev/null
+++ b/src/testing/fstest/testfs_test.go
@@ -0,0 +1,31 @@
+// Copyright 2021 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 (
+       "internal/testenv"
+       "os"
+       "path/filepath"
+       "testing"
+)
+
+func TestSymlink(t *testing.T) {
+       testenv.MustHaveSymlink(t)
+
+       tmp := t.TempDir()
+       tmpfs := os.DirFS(tmp)
+
+       if err := os.WriteFile(filepath.Join(tmp, "hello"), []byte("hello, world\n"), 0644); err != nil {
+               t.Fatal(err)
+       }
+
+       if err := os.Symlink(filepath.Join(tmp, "hello"), filepath.Join(tmp, "hello.link")); err != nil {
+               t.Fatal(err)
+       }
+
+       if err := TestFS(tmpfs, "hello", "hello.link"); err != nil {
+               t.Fatal(err)
+       }
+}