testing: robustify "relative" case in TestChdir against oldDir symlinks #75995
Description
Go version
go1.25.3 linux/amd64
Output of go env in your module/workspace:
On Linux (Ubuntu 24.04), go1.25.3/amd64
the TestChdir test in the standard library testing package:
when testing from a directory that contains a symlink in its current
path, the test may raise a false alarm.
$ pwd
/usr/local/dev-go/go/src/testing
$ ls -al /usr |grep local
lrwxrwxrwx 1 root root 21 Jun 3 22:03 local -> /mnt/oldrog/usr/localThis fixes it:
--- a/src/testing/testing_test.go
+++ b/src/testing/testing_test.go
@@ -299,7 +299,13 @@ func TestChdir(t *testing.T) {
if err != nil {
t.Fatal(err)
}
// The "relative" test case relies on tmp not being a symlink.
tmp, err := filepath.EvalSymlinks(t.TempDir())
if err != nil {
t.Fatal(err)
}
- rel, err := filepath.Rel(oldDir, tmp)
+ // The "relative" test case also relies on oldDir not containing symlinks.
+ oldDirNoSymLinks, err := filepath.EvalSymlinks(oldDir)
+ if err != nil {
+ t.Fatal(err)
+ }
+
+ rel, err := filepath.Rel(oldDirNoSymLinks, tmp)
if err != nil {
// If GOROOT is on C: volume and tmp is on the D: volume, there
Explanation: without the fix,
os.Getwd() returns '/usr/local/dev-go/go/src/testing' for oldDir.
however after resolving the symlinks in oldDir,
we obtain
oldDirNoSymLinks = '/mnt/oldrog/usr/local/dev-go/go/src/testing'
which means rel will have two more moves up on a fixed run.
rel='../../../../../../../../tmp/TestChdir2328321063/001'
With fix:
--- PASS: TestChdir (0.00s)
--- PASS: TestChdir/absolute (0.00s)
--- PASS: TestChdir/relative (0.00s)
--- PASS: TestChdir/current_(absolute) (0.00s)
--- PASS: TestChdir/current_(relative)_with_extra_os.Chdir (0.00s)
because:
filepath.Rel(oldDirNoSymLinks ='/mnt/oldrog/usr/local/dev-go/go/src/testing', tmp='/tmp/TestChdir1105991385/001') -> '../../../../../../../../tmp/TestChdir1105991385/001'
but without the fix, it fails, because it needs an additional '../..'
to get to the filesystem root.
=== RUN TestChdir/relative
tc.name = 'relative'
tmp0 = '/tmp/TestChdir66365355/001' // raw output of t.TempDir()
tmp = '/tmp/TestChdir66365355/001' // after tmp, err := filepath.EvalSymlinks(tmp0)
calling t.Chdir(tc.dir = '../../../../../../tmp/TestChdir66365355/001';
dir = '../../../../../../tmp/TestChdir66365355/001'
vs cwd = '/usr/local/dev-go/go/src/testing'
--- FAIL: TestChdir (0.00s)
--- PASS: TestChdir/absolute (0.00s)
--- FAIL: TestChdir/relative (0.00s)
panic: chdir ../../../../../../tmp/TestChdir66365355/001: no such file or directory [recovered, repanicked]
goroutine 1661 [running]:
testing.tRunner.func1.2({0x608880, 0xc0006840f0})
/usr/local/dev-go/go/src/testing/testing.go:1877 +0x237
testing.tRunner.func1()
/usr/local/dev-go/go/src/testing/testing.go:1880 +0x35b
panic({0x608880?, 0xc0006840f0?})
/mnt/oldrog/usr/local/dev-go/go/src/runtime/panic.go:783 +0x132
testing.(*common).Chdir(0xc000c83500, {0xc00032e090, 0x2b})
/usr/local/dev-go/go/src/testing/testing.go:1463 +0x2c5
testing.(*T).Chdir(0x6987b0?, {0xc00032e090?, 0x64a437?})
/usr/local/dev-go/go/src/testing/testing.go:1767 +0x45
testing_test.TestChdir.func1(0xc000c83500)
/usr/local/dev-go/go/src/testing/testing_test.go:352 +0x32f
testing.tRunner(0xc000c83500, 0xc000196150)
/usr/local/dev-go/go/src/testing/testing.go:1939 +0xea
created by testing.(*T).Run in goroutine 1687
/usr/local/dev-go/go/src/testing/testing.go:2002 +0x465
~~~
What did you do?
see above
What did you see happen?
see above
What did you expect to see?
see above