StringBuilder builder = new StringBuilder();
    Writer writer = new AppendableWriter(builder);

    writer.write("Hello".toCharArray());
    writer.write(',');
    writer.write(0xBEEF0020); // only lower 16 bits are important
    writer.write("Wo");
    writer.write("Whirled".toCharArray(), 3, 2);
    writer.write("Mad! Mad, I say", 2, 2);

    assertEquals("Hello, World!", builder.toString());
  }

   * @since 15.0 (in 14.0 with return type {@link BufferedWriter})
   */
  public Writer openBufferedStream() throws IOException {
    Writer writer = openStream();
    return (writer instanceof BufferedWriter)
        ? (BufferedWriter) writer
        : new BufferedWriter(writer);
  }

  /**
   * Writes the given character sequence to this sink.
   *

    Writer writer = sink.openStream();
    try {
      writer.write(data);
    } finally {
      writer.close();
    }

    assertContainsExpectedString();
  }

  public void testOpenBufferedStream() throws IOException {
    Writer writer = sink.openBufferedStream();
    try {
      writer.write(data);
    } finally {
      writer.close();
    }

    assertFalse(source.wasStreamClosed());

    StringWriter writer = new StringWriter();
    char[] buf = new char[64];
    int read;
    while ((read = reader.read(buf)) != -1) {
      writer.write(buf, 0, read);
    }
    reader.close();
    writer.close();

    assertTrue(source.wasStreamClosed());
    assertEquals(STRING, writer.toString());
  }

  public void testCopyTo_appendable() throws IOException {

  public void setUp() {
    sink = new TestCharSink();
  }

  public void testOpenBufferedStream() throws IOException {
    Writer writer = sink.openBufferedStream();
    assertTrue(sink.wasStreamOpened());
    assertFalse(sink.wasStreamClosed());

    writer.write(STRING);
    writer.close();

    assertTrue(sink.wasStreamClosed());
    assertEquals(STRING, sink.getString());
  }

    public CharSink createSink() throws IOException {
      File file = createFile();
      if (initialString != null) {
        Writer writer = new OutputStreamWriter(new FileOutputStream(file), Charsets.UTF_8);
        try {
          writer.write(initialString);
        } finally {
          writer.close();
        }
        return Files.asCharSink(file, Charsets.UTF_8, FileWriteMode.APPEND);
      }

      throws IOException {
    StringWriter writer = new StringWriter();
    try (OutputStream encodingStream = encoding.encodingStream(writer)) {
      encodingStream.write(decoded.getBytes(UTF_8));
    }
    assertThat(writer.toString()).isEqualTo(encoded);
  }

  @GwtIncompatible // Reader
  private static void testStreamingDecodes(BaseEncoding encoding, String encoded, String decoded)
      throws IOException {

import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.GenericDeclaration;
import java.lang.reflect.Type;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.nio.Buffer;

    assertFalse(source.wasStreamClosed());

    StringWriter writer = new StringWriter();
    char[] buf = new char[64];
    int read;
    while ((read = reader.read(buf)) != -1) {
      writer.write(buf, 0, read);
    }
    reader.close();
    writer.close();

    assertTrue(source.wasStreamClosed());
    assertEquals(STRING, writer.toString());
  }

  public void testLines() throws IOException {

    StringBuilder builder = new StringBuilder();
    Writer writer = new AppendableWriter(builder);

    writer.write("Hello".toCharArray());
    writer.write(',');
    writer.write(0xBEEF0020); // only lower 16 bits are important
    writer.write("Wo");
    writer.write("Whirled".toCharArray(), 3, 2);
    writer.write("Mad! Mad, I say", 2, 2);

    assertEquals("Hello, World!", builder.toString());
  }