* @param arrays zero or more {@code byte} arrays
   * @return a single array containing all the values from the source arrays, in order
   */
  public static byte[] concat(byte[]... arrays) {
    int length = 0;
    for (byte[] array : arrays) {
      length += array.length;
    }
    byte[] result = new byte[length];
    int pos = 0;
    for (byte[] array : arrays) {
      System.arraycopy(array, 0, result, pos, array.length);

        }
        int byte2 = bytes[index++];
        if (byte2 > (byte) 0xBF
            // Overlong? 5 most significant bits must not all be zero.
            || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0)
            // Check for illegal surrogate codepoints.
            || (byte1 == (byte) 0xED && (byte) 0xA0 <= byte2)
            // Third byte trailing-byte test.
            || bytes[index++] > (byte) 0xBF) {
          return false;

      actual += expected;
    }
    assertEquals(EXPECTED_FOUR_BYTE_ROUNDTRIPPABLE_COUNT, actual);
  }

  private static String newString(char... chars) {
    return new String(chars);
  }

  private static byte[] toByteArray(int... bytes) {
    byte[] realBytes = new byte[bytes.length];
    for (int i = 0; i < bytes.length; i++) {
      realBytes[i] = (byte) bytes[i];
    }
    return realBytes;
  }

              0x13579bdf,
              null,
              "df9b5713"),
          new ExpectedHashCode(
              new byte[] {(byte) 0xcd, (byte) 0xab, (byte) 0x00, (byte) 0x00},
              0x0000abcd,
              null,
              "cdab0000"),
          new ExpectedHashCode(
              new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x00,

  }

  MessageDigestHashFunction(String algorithmName, int bytes, String toString) {
    this.toString = checkNotNull(toString);
    this.prototype = getMessageDigest(algorithmName);
    int maxLength = prototype.getDigestLength();
    checkArgument(
        bytes >= 4 && bytes <= maxLength, "bytes (%s) must be >= 4 and < %s", bytes, maxLength);
    this.bytes = bytes;
    this.supportsClone = supportsClone(prototype);
  }

    assertFalse(sink.wasStreamClosed());

    out.write(new byte[] {1, 2, 3, 4});
    out.close();

    assertTrue(sink.wasStreamClosed());
    assertArrayEquals(new byte[] {1, 2, 3, 4}, sink.getBytes());
  }

  public void testWrite_bytes() throws IOException {
    assertArrayEquals(new byte[0], sink.getBytes());
    sink.write(bytes);

    assertTrue(sink.wasStreamOpened() && sink.wasStreamClosed());

  }

  static TestSuite suiteForBytes(
      ByteSourceFactory factory, byte[] bytes, String name, String desc, boolean slice) {
    TestSuite suite = new TestSuite(name + " [" + desc + "]");
    for (Method method : testMethods) {
      suite.addTest(new ByteSourceTester(factory, bytes, name, desc, method));
    }

    if (slice && bytes.length > 0) {
      // test a random slice() of the ByteSource

              0x13579bdf,
              null,
              "df9b5713"),
          new ExpectedHashCode(
              new byte[] {(byte) 0xcd, (byte) 0xab, (byte) 0x00, (byte) 0x00},
              0x0000abcd,
              null,
              "cdab0000"),
          new ExpectedHashCode(
              new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x00,

public interface Hasher extends PrimitiveSink {
  @CanIgnoreReturnValue
  @Override
  Hasher putByte(byte b);

  @CanIgnoreReturnValue
  @Override
  Hasher putBytes(byte[] bytes);

  @CanIgnoreReturnValue
  @Override
  Hasher putBytes(byte[] bytes, int off, int len);

  @CanIgnoreReturnValue
  @Override
  Hasher putBytes(ByteBuffer bytes);

  @CanIgnoreReturnValue
  @Override
  Hasher putShort(short s);

  }

  @SuppressWarnings("unchecked")
  static <T> T reserialize(T object) {
    try {
      ByteArrayOutputStream bytes = new ByteArrayOutputStream();
      ObjectOutputStream out = new ObjectOutputStream(bytes);
      out.writeObject(object);
      ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(bytes.toByteArray()));
      return (T) in.readObject();
    } catch (IOException | ClassNotFoundException e) {