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(

      TestCharSource failSource = new TestCharSource(STRING, option);
      TestCharSink okSink = new TestCharSink();
      assertThrows(IOException.class, () -> failSource.copyTo(okSink));
      // ensure writer was closed IF it was opened (depends on implementation whether or not it's
      // opened at all if source.newReader() 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(

      TestCharSource failSource = new TestCharSource(STRING, option);
      TestCharSink okSink = new TestCharSink();
      assertThrows(IOException.class, () -> failSource.copyTo(okSink));
      // ensure writer was closed IF it was opened (depends on implementation whether or not it's
      // opened at all if source.newReader() throws).
      assertTrue(

    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());
  }

}

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

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

    ByteArrayOutputStream out = new ByteArrayOutputStream();
    source.copyTo(out);
    assertExpectedBytes(out.toByteArray());
  }

  public void testCopyTo_byteSink() throws IOException {
    final ByteArrayOutputStream out = new ByteArrayOutputStream();
    // HERESY! but it's ok just for this I guess
    source.copyTo(
        new ByteSink() {
          @Override

    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()

    ByteArrayOutputStream out = new ByteArrayOutputStream();
    source.copyTo(out);
    assertExpectedBytes(out.toByteArray());
  }

  public void testCopyTo_byteSink() throws IOException {
    final ByteArrayOutputStream out = new ByteArrayOutputStream();
    // HERESY! but it's ok just for this I guess
    source.copyTo(
        new ByteSink() {
          @Override