assertEquals(expected, helper.toString());
    // Call toString again
    assertEquals(expected, helper.toString());

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

  public void testToString_minimal() {
    assertNotNull("toString() should not return null", collection.toString());
  }

  @CollectionSize.Require(ZERO)
  @CollectionFeature.Require(absent = NON_STANDARD_TOSTRING)
  public void testToString_size0() {
    assertEquals("emptyCollection.toString should return []", "[]", collection.toString());
  }

  @CollectionSize.Require(ONE)

  private final String toString;

  MessageDigestHashFunction(String algorithmName, String toString) {
    this.prototype = getMessageDigest(algorithmName);
    this.bytes = prototype.getDigestLength();
    this.toString = checkNotNull(toString);
    this.supportsClone = supportsClone(prototype);
  }

  MessageDigestHashFunction(String algorithmName, int bytes, String toString) {
    this.toString = checkNotNull(toString);

      return delegate.getId();
    }

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

  private interface Equals {
    @Override
    boolean equals(@Nullable Object obj);

    @Override
    int hashCode();

    @Override
    String toString();
  }

  private static class NoDelegateToEquals implements Equals {

  }

  // 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) {

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

  public void testKnownInputs_mixedAlgorithms() throws Exception {

    stopwatch.start();
    assertEquals("0.000 ns", stopwatch.toString());
    ticker.advance(1);
    assertEquals("1.000 ns", stopwatch.toString());
    ticker.advance(998);
    assertEquals("999.0 ns", stopwatch.toString());
    ticker.advance(1);
    assertEquals("1.000 \u03bcs", stopwatch.toString());
    ticker.advance(1);
    assertEquals("1.001 \u03bcs", stopwatch.toString());
    ticker.advance(8998);

    Checksum checksum = supplier.get();
    checksum.update(bytes, 0, bytes.length);
    long value = checksum.getValue();

    String toString = "name";
    HashFunction func = new ChecksumHashFunction(supplier, 32, toString);
    assertEquals(toString, func.toString());
    assertEquals(value, func.hashBytes(bytes).padToLong());
  }

  private static void assertHash32(

      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
    assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());
    assertEquals("[" + JOINER.join(map.keySet()) + "]", map.keySet().toString());
    assertEquals("[" + JOINER.join(map.values()) + "]", map.values().toString());

      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
      assertEquals(entry.getKey(), bimap.inverse().get(entry.getValue()));
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
    assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());
    assertEquals("[" + JOINER.join(map.keySet()) + "]", map.keySet().toString());