TestByteSource failSource = new TestByteSource(new byte[10], option);
      TestByteSink okSink = new TestByteSink();
      assertThrows(IOException.class, () -> failSource.copyTo(okSink));
      // ensure stream was closed IF it was opened (depends on implementation whether or not it's
      // opened at all if source.newInputStream() throws).
      assertTrue(

      TestByteSource failSource = new TestByteSource(new byte[10], option);
      TestByteSink okSink = new TestByteSink();
      assertThrows(IOException.class, () -> failSource.copyTo(okSink));
      // ensure stream was closed IF it was opened (depends on implementation whether or not it's
      // opened at all if source.newInputStream() throws).
      assertTrue(

}

internal class BufferMockResponseBody(
  val buffer: Buffer,
) : MockResponseBody {
  override val contentLength = buffer.size

  override fun writeTo(sink: BufferedSink) {
    buffer.copyTo(sink.buffer)
    sink.emitCompleteSegments()
  }

   *       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

      },
      "content": {
        "type": "text",
        "analyzer": "standard_analyzer",
        "search_analyzer": "standard_search_analyzer",
        "term_vector": "with_positions_offsets",
        "copy_to": ["content_minhash_bits"]
      },
      "content_minhash": {
        "type": "text",
        "index": false
      },
      "content_minhash_bits": {
        "type": "minhash",
        "bit_string": true,

    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());
  }

 * signatures.
 */
fun Buffer.isProbablyUtf8(): Boolean {
  try {
    val prefix = Buffer()
    val byteCount = size.coerceAtMost(64)
    copyTo(prefix, 0, byteCount)
    for (i in 0 until 16) {
      if (prefix.exhausted()) {
        break
      }
      val codePoint = prefix.readUtf8CodePoint()

          }

          // 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) {

   *
   * @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);