assertTrue(name, domain.hasPublicSuffix());
      assertTrue(name, domain.isUnderPublicSuffix());
    }
  }

  public void testUnderPublicSuffix() {
    for (String name : SOMEWHERE_UNDER_PS) {
      InternetDomainName domain = InternetDomainName.from(name);
      assertFalse(name, domain.isPublicSuffix());
      assertTrue(name, domain.hasPublicSuffix());
      assertTrue(name, domain.isUnderPublicSuffix());

   * @since 6.0
   */
  public boolean hasPublicSuffix() {
    return publicSuffixIndex() != NO_SUFFIX_FOUND;
  }

  /**
   * Returns the {@linkplain #isPublicSuffix() public suffix} portion of the domain name, or {@code
   * null} if no public suffix is present.
   *
   * @since 6.0
   */
  public @Nullable InternetDomainName publicSuffix() {
    return hasPublicSuffix() ? ancestor(publicSuffixIndex()) : null;
  }

    // TODO(user): different versions of this for different factories?
    InternetDomainName domain = InternetDomainName.from(host);

    if (domain.hasPublicSuffix()) {
      return new HostSpecifier(domain.toString());
    }

    throw new IllegalArgumentException(
        "Domain name does not have a recognized public suffix: " + host);
  }

  /**