assertEquals(hashFunction.hashBytes(bytes), hashFunction.hashBytes(ByteBuffer.wrap(bytes)));
  }

  static void assertHashByteBufferExhaustsBuffer(HashFunction hashFunction) {
    Random rng = new Random(0L);
    byte[] bytes = new byte[rng.nextInt(256) + 1];
    rng.nextBytes(bytes);
    ByteBuffer buffer = ByteBuffer.wrap(bytes);
    HashCode unused = hashFunction.hashBytes(buffer);

    Mac mac = Mac.getInstance(algorithm);
    mac.init(key);
    mac.update(input);

    assertEquals(HashCode.fromBytes(mac.doFinal()), hashFunc.hashBytes(input));
    assertEquals(HashCode.fromBytes(mac.doFinal(input)), hashFunc.hashBytes(input));
  }

  // Tests from RFC2022: https://tools.ietf.org/html/rfc2202

  public void testRfc2202_hmacSha1_case1() {
    byte[] key = fillByteArray(20, 0x0b);

          shift -= 32;
        }
      }

      int k1 = mixK1((int) buffer);
      h1 ^= k1;
      return fmix(h1, len);
    } else {
      return hashBytes(input.toString().getBytes(charset));
    }
  }

  @Override
  public HashCode hashBytes(byte[] input, int off, int len) {
    checkPositionIndexes(off, off + len, input.length);
    int h1 = seed;
    int i;

          shift -= 32;
        }
      }

      int k1 = mixK1((int) buffer);
      h1 ^= k1;
      return fmix(h1, len);
    } else {
      return hashBytes(input.toString().getBytes(charset));
    }
  }

  @Override
  public HashCode hashBytes(byte[] input, int off, int len) {
    checkPositionIndexes(off, off + len, input.length);
    int h1 = seed;
    int i;

    assertTrue(hashCode.bits() >= 32); // sanity
    byte[] hashBytes = hashCode.asBytes();
    int totalBytes = hashCode.bits() / 8;

    for (int bytes = 0; bytes < totalBytes; bytes++) {
      byte[] bb = new byte[bytes];
      hashCode.writeBytesTo(bb, 0, bb.length);

      assertTrue(Arrays.equals(Arrays.copyOf(hashBytes, bytes), bb));
    }
  }

  private static class ExpectedHashCode {

    assertTrue(hashCode.bits() >= 32); // sanity
    byte[] hashBytes = hashCode.asBytes();
    int totalBytes = hashCode.bits() / 8;

    for (int bytes = 0; bytes < totalBytes; bytes++) {
      byte[] bb = new byte[bytes];
      hashCode.writeBytesTo(bb, 0, bb.length);

      assertTrue(Arrays.equals(Arrays.copyOf(hashBytes, bytes), bb));
    }
  }

  private static class ExpectedHashCode {

  }

  public void testHashIntReverseBytesVsHashBytesIntsToByteArray() {
    int input = 42;
    assertEquals(
        Hashing.md5().hashBytes(Ints.toByteArray(input)),
        Hashing.md5().hashInt(Integer.reverseBytes(input)));
  }

  public void testHashIntVsForLoop() {
    int input = 42;
    HashCode expected = Hashing.md5().hashInt(input);

  }

  public void testHashIntReverseBytesVsHashBytesIntsToByteArray() {
    int input = 42;
    assertEquals(
        Hashing.md5().hashBytes(Ints.toByteArray(input)),
        Hashing.md5().hashInt(Integer.reverseBytes(input)));
  }

  public void testHashIntVsForLoop() {
    int input = 42;
    HashCode expected = Hashing.md5().hashInt(input);

      output.write(bytes, offset, length);
      return length;
    }

    @Override
    public HashCode hash(HashFunction hashFunction) throws IOException {
      return hashFunction.hashBytes(bytes, offset, length);
    }

    @Override
    public ByteSource slice(long offset, long length) {
      checkArgument(offset >= 0, "offset (%s) may not be negative", offset);