Fix test to workaround docker credstore symlink fault

As described in containerd#3413 there seems to be a fault
in docker credentials store that makes relative symlinks resolve to pwd instead of where they are.
This in turn will break our test if the current working directory is read-only (typical with Lima).
This changeset does Chdir to the parent temp directory so we can workaround that problem.

Signed-off-by: apostasie <[email protected]>

pkg/imgutil/dockerconfigresolver/credentialsstore_test.go

@@ -168,7 +168,8 @@ func TestBrokenCredentialsStore(t *testing.T) {
 		},
 	}
 
-	t.Run("Broken Docker Config testing", func(t *testing.T) {
+	t.Run("Docker Config testing with a variety of filesystem situations", func(t *testing.T) {
+		// Do NOT parallelize this test, as it relies on Chdir, which would have side effects for other tests.
 		registryURL, err := Parse("registry")
 		if err != nil {
 			t.Fatal(err)
@@ -177,6 +178,16 @@ func TestBrokenCredentialsStore(t *testing.T) {
 		for _, tc := range testCases {
 			t.Run(tc.description, func(t *testing.T) {
 				directory := tc.setup()
+				// See https://github.com/containerd/nerdctl/issues/3413
+				oldpwd, err := os.Getwd()
+				assert.NilError(t, err)
+				// Ignore the error, as the destination may not be a directory
+				_ = os.Chdir(directory)
+				t.Cleanup(func() {
+					err = os.Chdir(oldpwd)
+					assert.NilError(t, err)
+				})
+
 				cs, err := NewCredentialsStore(directory)
 				assert.ErrorIs(t, err, tc.errorNew)
 				if err != nil {
@@ -189,6 +200,7 @@ func TestBrokenCredentialsStore(t *testing.T) {
 
 				err = cs.Store(registryURL, af)
 				assert.ErrorIs(t, err, tc.errorWrite)
+
 			})
 		}
 	})