* overflow and return null.
   */
  @Test fun overflowEncodingOversizedLabel() {
    val a1000 = "a".repeat(1000)
    val a1000MaxCodePoint = a1000 + "\udbff\udfff"
    testEncodeDecode(
      a1000MaxCodePoint,
      "xn--$a1000-nc89312g",
    )
    assertNull(
      Punycode.encode(a1000MaxCodePoint.repeat(2)),
    )
  }

  @Test fun invalidPunycode() {
    assertNull(Punycode.decode("xn--ls8h="))
  }