// Make sure we expected this.
      assertThat(expectHost).isNull();
      return;
    }
    assertThat(expectHost).isNotNull();

    // Apply withDefaultPort(), yielding hp2.
    boolean badDefaultPort = defaultPort < 0 || defaultPort > 65535;
    HostAndPort hp2 = null;
    try {
      hp2 = hp.withDefaultPort(defaultPort);
      assertFalse(badDefaultPort);