InternetDomainName googleDomain = InternetDomainName.from("google.com");

    assertEquals(googleDomain, googleDomain.topPrivateDomain());
    assertEquals(googleDomain, googleDomain.child("mail").topPrivateDomain());
    assertEquals(googleDomain, googleDomain.child("foo.bar").topPrivateDomain());
  }

  public void testInvalidTopPrivateDomain() {

    HostAndPort hp = HostAndPort.fromParts("gmail.com", 81);
    assertEquals("gmail.com", hp.getHost());
    assertTrue(hp.hasPort());
    assertEquals(81, hp.getPort());

    try {
      HostAndPort.fromParts("gmail.com:80", 81);
      fail("Expected IllegalArgumentException");
    } catch (IllegalArgumentException expected) {
    }

    try {
      HostAndPort.fromParts("gmail.com", -1);

    InternetDomainName googleDomain = InternetDomainName.from("google.com");

    assertEquals(googleDomain, googleDomain.topPrivateDomain());
    assertEquals(googleDomain, googleDomain.child("mail").topPrivateDomain());
    assertEquals(googleDomain, googleDomain.child("foo.bar").topPrivateDomain());
  }

  public void testInvalidTopPrivateDomain() {

    }

    return true;
  }

  /**
   * Returns the individual components of this domain name, normalized to all lower case. For
   * example, for the domain name {@code mail.google.com}, this method returns the list {@code
   * ["mail", "google", "com"]}.
   */
  public ImmutableList<String> parts() {
    return parts;
  }

  /**