assertThat(helper.toString()).isEqualTo(expected);
    // Call toString again
    assertThat(helper.toString()).isEqualTo(expected);

    // Make sure the cached value is reset when we modify the helper at all
    String expected2 = "TestClass{field1=1, value1, field2=value2, 2}";
    helper.addValue(2);
    assertThat(helper.toString()).isEqualTo(expected2);
  }

    assertThat(HashCode.fromBytes(mac.doFinal()).toString()).isEqualTo(knownOutput);
    assertThat(HashCode.fromBytes(mac.doFinal(input.getBytes(UTF_8))).toString())
        .isEqualTo(knownOutput);
    assertThat(hmacMd5(MD5_KEY).hashString(input, UTF_8).toString()).isEqualTo(knownOutput);
    assertThat(hmacMd5(MD5_KEY).hashBytes(input.getBytes(UTF_8)).toString()).isEqualTo(knownOutput);
  }

              @Override
              public String toString() {
                return runnable.toString();
              }
            });
  }

  public void testFailsToForwardToString() {
    assertFailure(
        Runnable.class,
        runnable ->
            new ForwardingRunnable(runnable) {
              @Override
              public String toString() {
                return "";
              }

  // A simple type whose .toString() will return the same value each time, but without maintaining
  // a strong reference to that value.
  static class Key {
    private final int value;
    private WeakReference<String> toString;

    Key(int value) {
      this.value = value;
    }

    @Override
    public synchronized String toString() {
      String s;
      if (toString != null) {

              @Override
              public String toString() {
                return runnable.toString();
              }
            });
  }

  public void testFailsToForwardToString() {
    assertFailure(
        Runnable.class,
        runnable ->
            new ForwardingRunnable(runnable) {
              @Override
              public String toString() {
                return "";
              }

    assertThat(HostAndPort.fromString("foo:101").toString()).isEqualTo("foo:101");
    assertThat(HostAndPort.fromString(":102").toString()).isEqualTo(":102");
    assertThat(HostAndPort.fromParts("1::2", 103).toString()).isEqualTo("[1::2]:103");
    assertThat(HostAndPort.fromString("[::1]:104").toString()).isEqualTo("[::1]:104");

    // Without ports.
    assertThat(HostAndPort.fromString("foo").toString()).isEqualTo("foo");

    assertThat(HostAndPort.fromString("foo:101").toString()).isEqualTo("foo:101");
    assertThat(HostAndPort.fromString(":102").toString()).isEqualTo(":102");
    assertThat(HostAndPort.fromParts("1::2", 103).toString()).isEqualTo("[1::2]:103");
    assertThat(HostAndPort.fromString("[::1]:104").toString()).isEqualTo("[::1]:104");

    // Without ports.
    assertThat(HostAndPort.fromString("foo").toString()).isEqualTo("foo");

    HashCode hash2 = HashCode.fromString(hash1.toString());
    assertEquals(hash1, hash2);
  }

  public void testRoundTrip() {
    for (ExpectedHashCode expected : expectedHashCodes) {
      String string = HashCode.fromBytes(expected.bytes).toString();
      assertThat(string).isEqualTo(expected.toString);
      assertThat(HashCode.fromBytes(BaseEncoding.base16().lowerCase().decode(string)).toString())
          .isEqualTo(expected.toString);

    HashCode hash2 = HashCode.fromString(hash1.toString());
    assertEquals(hash1, hash2);
  }

  public void testRoundTrip() {
    for (ExpectedHashCode expected : expectedHashCodes) {
      String string = HashCode.fromBytes(expected.bytes).toString();
      assertThat(string).isEqualTo(expected.toString);
      assertThat(HashCode.fromBytes(BaseEncoding.base16().lowerCase().decode(string)).toString())
          .isEqualTo(expected.toString);

  @SuppressWarnings("deprecation") // We still need to test our deprecated APIs.
  public void testToString() {
    assertThat(md5().toString()).isEqualTo("Hashing.md5()");
    assertThat(sha1().toString()).isEqualTo("Hashing.sha1()");
    assertThat(sha256().toString()).isEqualTo("Hashing.sha256()");
    assertThat(sha512().toString()).isEqualTo("Hashing.sha512()");
  }

  private static void assertMessageDigestHashing(byte[] input, String algorithmName)