assertFalse(writer.closed());
    source.copyTo(writer);
    assertFalse(writer.closed());
  }

  public void testClosesOnErrors_copyingToCharSinkThatThrows() {
    for (TestOption option : EnumSet.of(OPEN_THROWS, WRITE_THROWS, CLOSE_THROWS)) {
      TestCharSource okSource = new TestCharSource(STRING);
      assertThrows(IOException.class, () -> okSource.copyTo(new TestCharSink(option)));

    assertFalse(writer.closed());
    source.copyTo(writer);
    assertFalse(writer.closed());
  }

  public void testClosesOnErrors_copyingToCharSinkThatThrows() {
    for (TestOption option : EnumSet.of(OPEN_THROWS, WRITE_THROWS, CLOSE_THROWS)) {
      TestCharSource okSource = new TestCharSource(STRING);
      assertThrows(IOException.class, () -> okSource.copyTo(new TestCharSink(option)));

    Set<Object> set = new HashSet<>();
    assertThat(union(emptySet(), emptySet()).copyInto(set)).isSameInstanceAs(set);
    assertThat(intersection(emptySet(), emptySet()).copyInto(set)).isSameInstanceAs(set);
    assertThat(difference(emptySet(), emptySet()).copyInto(set)).isSameInstanceAs(set);
    assertThat(symmetricDifference(emptySet(), emptySet()).copyInto(set)).isSameInstanceAs(set);
  }

  public void testCopyInto_emptySet() {

   *       one with {@link CharSequence#charAt(int)}.
   *   <li>use {@link Appendable#append(CharSequence)} in {@link #copyTo(Appendable)} and {@link
   *       #copyTo(CharSink)}. We know this is correct since strings are immutable and so the length
   *       can't change, and it is faster because many writers and appendables are optimized for

   *       one with {@link CharSequence#charAt(int)}.
   *   <li>use {@link Appendable#append(CharSequence)} in {@link #copyTo(Appendable)} and {@link
   *       #copyTo(CharSink)}. We know this is correct since strings are immutable and so the length
   *       can't change, and it is faster because many writers and appendables are optimized for

    StringBuilder builder = new StringBuilder();

    assertEquals(expected.length(), source.copyTo(builder));

    assertExpectedString(builder.toString());
  }

  public void testCopyTo_charSink() throws IOException {
    TestCharSink sink = new TestCharSink();

    assertEquals(expected.length(), source.copyTo(sink));

    assertExpectedString(sink.getString());
  }

          }

          // The buffer has the data we need. Read from there and return immediately.
          val bytesToRead = minOf(byteCount, upstreamPos - sourcePos)
          buffer.copyTo(sink, sourcePos - bufferPos, bytesToRead)
          sourcePos += bytesToRead
          return bytesToRead
        }

      // Read from the file.
      if (source == SOURCE_FILE) {

   * @deprecated Prefer {@code asCharSource(from, charset).copyTo(to)}.
   */
  @Deprecated
  @InlineMe(
      replacement = "Files.asCharSource(from, charset).copyTo(to)",
      imports = "com.google.common.io.Files")
  public
  static void copy(File from, Charset charset, Appendable to) throws IOException {
    asCharSource(from, charset).copyTo(to);
  }

  /**

   *
   * @return the number of bytes copied
   * @throws IOException if an I/O error occurs while reading from this source or writing to {@code
   *     output}
   */
  @CanIgnoreReturnValue
  public long copyTo(OutputStream output) throws IOException {
    checkNotNull(output);

    Closer closer = Closer.create();
    try {
      InputStream in = closer.register(openStream());
      return ByteStreams.copy(in, output);

          nameBuf.writeByte(utf8ByteCount.toInt())
          nameBuf.writeUtf8(label)
        }
        nameBuf.writeByte(0) // end

        nameBuf.copyTo(this, 0, nameBuf.size)
        writeShort(type)
        writeShort(1) // CLASS_IN
      }.readByteString()

  @Throws(Exception::class)
  fun decodeAnswers(
    hostname: String,
    byteString: ByteString,