*
   * @return the number of characters written
   * @throws IOException if an I/O error occurs while reading from {@code readable} or writing to
   *     this sink
   */
  @CanIgnoreReturnValue
  public long writeFrom(Readable readable) throws IOException {
    checkNotNull(readable);

    try (Writer out = openStream()) {
      return CharStreams.copy(readable, out);
    }
  }

    StringReader reader = new StringReader(STRING);
    sink.writeFrom(reader);

    assertTrue(sink.wasStreamOpened() && sink.wasStreamClosed());
    assertThat(sink.getString()).isEqualTo(STRING);
  }

  public void testWriteFromStream_doesNotCloseThatStream() throws IOException {
    TestReader in = new TestReader();
    assertFalse(in.closed());
    sink.writeFrom(in);
    assertFalse(in.closed());
  }

    StringReader reader = new StringReader(STRING);
    sink.writeFrom(reader);

    assertTrue(sink.wasStreamOpened() && sink.wasStreamClosed());
    assertThat(sink.getString()).isEqualTo(STRING);
  }

  public void testWriteFromStream_doesNotCloseThatStream() throws IOException {
    TestReader in = new TestReader();
    assertFalse(in.closed());
    sink.writeFrom(in);
    assertFalse(in.closed());
  }