/**
   * Returns a {@link Writer} that simply discards written chars.
   *
   * @since 15.0
   */
  public static Writer nullWriter() {
    return NullWriter.INSTANCE;
  }

  private static final class NullWriter extends Writer {

    private static final NullWriter INSTANCE = new NullWriter();

    @Override
    public void write(int c) {}

    @Override
    public void write(char[] cbuf) {

    // create a null writer
    Writer nullWriter = CharStreams.nullWriter();
    // write to the writer
    nullWriter.write('n');
    String test = "Test string for NullWriter";
    nullWriter.write(test);
    nullWriter.write(test, 2, 10);
    nullWriter.append(null);
    nullWriter.append(null, 0, 4);

    assertThrows(IndexOutOfBoundsException.class, () -> nullWriter.append(null, -1, 4));

    // create a null writer
    Writer nullWriter = CharStreams.nullWriter();
    // write to the writer
    nullWriter.write('n');
    String test = "Test string for NullWriter";
    nullWriter.write(test);
    nullWriter.write(test, 2, 10);
    nullWriter.append(null);
    nullWriter.append(null, 0, 4);

    assertThrows(IndexOutOfBoundsException.class, () -> nullWriter.append(null, -1, 4));