TestSha1Sum should not fail if file open successful

[demizer]

func TestSha1Sum(t *testing.T) {
    _, err := sha1sum("/root")
    if err == nil {
        t.Error("EXPECT: error permission denied GOT: No errors")
    }
}

Root user can read "/root", so this test will fail if being run by root user. This test should not fail if being run by a privileged user.