@Test
  fun hostIpv6WithIpv4SuffixWithHexadecimalPrefix() {
    // Chrome interprets a leading '0x' as hexadecimal; Firefox rejects them. (We reject them.)
    assertInvalid(
      "http://[0:0:0:0:0:1:0.0x10.0.0x10]/",
      "Invalid URL host: \"[0:0:0:0:0:1:0.0x10.0.0x10]\"",
    )
  }

  @Test
  fun hostIpv6WithMalformedIpv4Suffix() {
    assertInvalid(
      "http://[0:0:0:0:0:1:0.0:0.0]/",

            @Override
            public CacheStats snapshot() {
              return EMPTY_STATS;
            }
          });
  static final CacheStats EMPTY_STATS = new CacheStats(0, 0, 0, 0, 0, 0);

  /*
   * We avoid using a method reference or lambda here for now:
   *
   * - method reference: Inside Google, CacheBuilder is used from the implementation of a custom

 * href="http://www.unicode.org/glossary/#BMP_character">BMP characters</a>. It does not understand
 * <a href="http://www.unicode.org/glossary/#supplementary_code_point">supplementary Unicode code
 * points</a> in the range {@code 0x10000} to {@code 0x10FFFF} which includes the majority of
 * assigned characters, including important CJK characters and emoji.
 *
 * <p>Supplementary characters are <a