fileutils_test: check symlink directory location before test

In macOS and maybe some other systems, /tmp is a symlink to /private/tmp
or some other similar directory, so ReadSymlinkedDirectory ends up pointing
at a different directory than was created. Get the evaluated path of the
directory being created, and compare that to the result of
ReadSymlinkedDirectory.

Signed-off-by: Caleb Xu <caxu@redhat.com>

Author: caxu-rh

storage/pkg/fileutils/fileutils_test.go

@@ -120,6 +120,11 @@ func TestReadSymlinkedDirectoryExistingDirectory(t *testing.T) {
 		t.Errorf("failed to create directory: %s", err)
 	}
 
+	var realpath string
+	if realpath, err = filepath.EvalSymlinks("/tmp/testReadSymlinkToExistingDirectory"); err != nil {
+		t.Errorf("failed to evaluate symlinks in path: %s", err)
+	}
+
 	if err = os.Symlink("/tmp/testReadSymlinkToExistingDirectory", "/tmp/dirLinkTest"); err != nil {
 		t.Errorf("failed to create symlink: %s", err)
 	}
@@ -129,7 +134,7 @@ func TestReadSymlinkedDirectoryExistingDirectory(t *testing.T) {
 		t.Fatalf("failed to read symlink to directory: %s", err)
 	}
 
-	if path != "/tmp/testReadSymlinkToExistingDirectory" {
+	if path != realpath {
 		t.Fatalf("symlink returned unexpected directory: %s", path)
 	}