OutputStream out = Funnels.asOutputStream(sink);
    byte[] bytes = {1, 2, 3, 4};
    out.write(255);
    out.write(bytes);
    out.write(bytes, 1, 2);
    verify(sink).putByte((byte) 255);
    verify(sink).putBytes(bytes);
    verify(sink).putBytes(bytes, 1, 2);
  }

  public void testSerialization() {
    assertSame(
        Funnels.byteArrayFunnel(), SerializableTester.reserialize(Funnels.byteArrayFunnel()));

    verify(hasher).putByte((byte) b);
    verifyNoMoreInteractions(hashFunction, hasher);
  }

  public void testWrite_putByteArray() throws Exception {
    byte[] buf = new byte[] {'y', 'a', 'm', 's'};
    HashingOutputStream out = new HashingOutputStream(hashFunction, buffer);
    out.write(buf);

    verify(hashFunction).newHasher();
    verify(hasher).putBytes(buf, 0, buf.length);

    this.hasher = checkNotNull(hashFunction.newHasher());
  }

  @Override
  public void write(int b) throws IOException {
    hasher.putByte((byte) b);
    out.write(b);
  }

  @Override
  public void write(byte[] bytes, int off, int len) throws IOException {
    hasher.putBytes(bytes, off, len);
    out.write(bytes, off, len);
  }

  /**

    this.hasher = checkNotNull(hashFunction.newHasher());
  }

  @Override
  public void write(int b) throws IOException {
    hasher.putByte((byte) b);
    out.write(b);
  }

  @Override
  public void write(byte[] bytes, int off, int len) throws IOException {
    hasher.putBytes(bytes, off, len);
    out.write(bytes, off, len);
  }

  /**

    }

    @Override
    public Hasher putByte(byte b) {
      stream.write(b);
      return this;
    }

    @Override
    public Hasher putBytes(byte[] bytes, int off, int len) {
      stream.write(bytes, off, len);
      return this;
    }

    @Override
    public Hasher putBytes(ByteBuffer bytes) {
      stream.write(bytes);
      return this;
    }

   * byte read.
   */
  @Override
  @CanIgnoreReturnValue
  public int read() throws IOException {
    int b = in.read();
    if (b != -1) {
      hasher.putByte((byte) b);
    }
    return b;
  }

  /**
   * Reads the specified bytes of data from the underlying input stream and updates the hasher with
   * the bytes read.
   */
  @Override
  @CanIgnoreReturnValue

    process(bb);
  }

  @Override
  @CanIgnoreReturnValue
  public final Hasher putBytes(byte[] bytes, int off, int len) {
    return putBytesInternal(ByteBuffer.wrap(bytes, off, len).order(ByteOrder.LITTLE_ENDIAN));
  }

  @Override
  @CanIgnoreReturnValue
  public final Hasher putBytes(ByteBuffer readBuffer) {
    ByteOrder order = readBuffer.order();
    try {

  }

  public void testRead_putSingleByte() throws Exception {
    HashingInputStream in = new HashingInputStream(hashFunction, buffer);

    int b = in.read();
    assertEquals('y', b);

    verify(hasher).putByte((byte) 'y');
    verify(hashFunction).newHasher();
    verifyNoMoreInteractions(hashFunction, hasher);
  }

  public void testRead_putByteArray() throws Exception {

  }

  public void testRead_putSingleByte() throws Exception {
    HashingInputStream in = new HashingInputStream(hashFunction, buffer);

    int b = in.read();
    assertEquals('y', b);

    verify(hasher).putByte((byte) 'y');
    verify(hashFunction).newHasher();
    verifyNoMoreInteractions(hashFunction, hasher);
  }

  public void testRead_putByteArray() throws Exception {

   *
   * @param b a byte
   * @return this instance
   */
  @CanIgnoreReturnValue
  PrimitiveSink putByte(byte b);

  /**
   * Puts an array of bytes into this sink.
   *
   * @param bytes a byte array
   * @return this instance
   */
  @CanIgnoreReturnValue
  PrimitiveSink putBytes(byte[] bytes);

  /**
   * Puts a chunk of an array of bytes into this sink. {@code bytes[off]} is the first byte written,