*/
  public abstract OutputStream openStream() throws IOException;

  /**
   * Opens a new buffered {@link OutputStream} for writing to this sink. The returned stream is not
   * required to be a {@link BufferedOutputStream} in order to allow implementations to simply
   * delegate to {@link #openStream()} when the stream returned by that method does not benefit from

   */
  public abstract OutputStream openStream() throws IOException;

  /**
   * Opens a new buffered {@link OutputStream} for writing to this sink. The returned stream is not
   * required to be a {@link BufferedOutputStream} in order to allow implementations to simply
   * delegate to {@link #openStream()} when the stream returned by that method does not benefit from

    CharSource reader =
        new CharSource() {
          @Override
          public Reader openStream() throws IOException {
            if (counter[0]++ != 0) {
              throw new IllegalStateException("More than one source open");
            }
            return new FilterReader(source.openStream()) {
              @Override
              public void close() throws IOException {
                super.close();

   */
  public abstract Writer openStream() throws IOException;

  /**
   * Opens a new buffered {@link Writer} for writing to this sink. The returned stream is not
   * required to be a {@link BufferedWriter} in order to allow implementations to simply delegate to
   * {@link #openStream()} when the stream returned by that method does not benefit from additional

    ByteSource checker =
        new ByteSource() {
          @Override
          public InputStream openStream() throws IOException {
            if (counter[0]++ != 0) {
              throw new IllegalStateException("More than one source open");
            }
            return new FilterInputStream(source.openStream()) {
              @Override
              public void close() throws IOException {
                super.close();

  }

  @Override
  public boolean wasStreamClosed() {
    return byteSource.wasStreamClosed();
  }

  @Override
  public Reader openStream() throws IOException {
    return new InputStreamReader(byteSource.openStream(), UTF_8);
  }

    ByteSource checker =
        new ByteSource() {
          @Override
          public InputStream openStream() throws IOException {
            if (counter[0]++ != 0) {
              throw new IllegalStateException("More than one source open");
            }
            return new FilterInputStream(source.openStream()) {
              @Override
              public void close() throws IOException {
                super.close();

  @Override
  public boolean wasStreamClosed() {
    return byteSink.wasStreamClosed();
  }

  @Override
  public Writer openStream() throws IOException {
    // using TestByteSink's output stream to get option behavior, so flush to it on every write
    return new FilterWriter(new OutputStreamWriter(byteSink.openStream(), UTF_8)) {
      @Override
      public void write(int c) throws IOException {
        super.write(c);
        flush();

  }

  /** A byte source that reads from a URL using {@link URL#openStream()}. */
  private static final class UrlByteSource extends ByteSource {

    private final URL url;

    private UrlByteSource(URL url) {
      this.url = checkNotNull(url);
    }

    @Override
    public InputStream openStream() throws IOException {
      return url.openStream();
    }

    @Override
    public String toString() {

      @Override
      String read(ByteSource byteSource, Charset cs) throws IOException {
        StringBuilder sb = new StringBuilder();
        try (InputStreamReader reader = new InputStreamReader(byteSource.openStream(), cs)) {
          CharStreams.copy(reader, sb);
        }
        return sb.toString();
      }
    },
    // It really seems like this should be faster than TO_BYTE_ARRAY_NEW_STRING.  But it just isn't