oldSalt := hashSalt
	hashSalt = nil
	defer func() {
		hashSalt = oldSalt
	}()

	h := NewHash("alice")
	h.Write([]byte("hello world"))
	sum := fmt.Sprintf("%x", h.Sum())
	want := "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
	if sum != want {
		t.Errorf("hash(hello world) = %v, want %v", sum, want)
	}
}

func TestHashFile(t *testing.T) {
	f, err := os.CreateTemp("", "cmd-go-test-")
	if err != nil {