* ### Duplex APIs
   *
   * With regular request bodies it is not legal to write bytes to the sink passed to
   * [RequestBody.writeTo] after that method returns. For duplex requests bodies that condition is
   * lifted. Such writes occur on an application-provided thread and may occur concurrently with
   * reads of the [ResponseBody]. For duplex request bodies, [writeTo] should return

	{"ReadByte", func(r *Reader) { r.ReadByte() }},
	{"UnreadRune", func(r *Reader) { r.UnreadRune() }},
	{"Seek", func(r *Reader) { r.Seek(0, io.SeekCurrent) }},
	{"WriteTo", func(r *Reader) { r.WriteTo(&Buffer{}) }},
}

func TestUnreadRuneError(t *testing.T) {
	for _, tt := range UnreadRuneErrorTests {
		reader := NewReader([]byte("0123456789"))
		if _, _, err := reader.ReadRune(); err != nil {

    assertOnFileDescriptor(content = "Hello") { fd ->
      val requestBody = fd.toRequestBody()

      val buffer = Buffer()
      requestBody.writeTo(buffer)
      assertThat(buffer.readUtf8()).isEqualTo("Hello")

      assertThrows(IOException::class.java) {
        requestBody.writeTo(Buffer())
      }
    }
  }

  @Test
  fun testFileDescriptorAfterClose() {

	}
	r.i = abs
	return abs, nil
}

// WriteTo implements the [io.WriterTo] interface.
func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
	r.prevRune = -1
	if r.i >= int64(len(r.s)) {
		return 0, nil
	}
	b := r.s[r.i:]
	m, err := w.Write(b)
	if m > len(b) {
		panic("bytes.Reader.WriteTo: invalid Write count")
	}
	r.i += int64(m)
	n = int64(m)

            requestBody.writeTo(bufferedRequestBody)
          } else {
            // Write the request body if the "Expect: 100-continue" expectation was met.
            val bufferedRequestBody = exchange.createRequestBody(request, false).buffer()
            requestBody.writeTo(bufferedRequestBody)
            bufferedRequestBody.close()
          }
        } else {

    val out = Buffer()
    body.writeTo(out)
    assertThat(out.readUtf8()).isEqualTo(expected)
  }

  @Test
  fun encodedPair() {
    val body =
      FormBody.Builder()
        .add("sim", "ple")
        .build()
    val expected = "sim=ple"
    assertThat(body.contentLength()).isEqualTo(expected.length.toLong())
    val buffer = Buffer()
    body.writeTo(buffer)

  return object : RequestBody() {
    override fun contentType() = contentType

    override fun contentLength() = byteCount.toLong()

    override fun writeTo(sink: BufferedSink) {
      sink.write(this@commonToRequestBody, offset, byteCount)
    }
  }
}

@Suppress("unused")
fun RequestBody.commonContentLength(): Long = -1L

@Suppress("unused")

    return object : ForwardingSink(sink) {
      @Throws(IOException::class)
      override fun write(
        source: Buffer,
        byteCount: Long,
      ) {
        val bytes = source.readByteString(byteCount)
        delegate.write(
          Buffer()
            .write(bytes.toAsciiUppercase()),
          byteCount,
        )
      }
    }
  }

  }

  @Throws(IOException::class)
  override fun contentLength(): Long {
    return delegate.contentLength()
  }

  @Throws(IOException::class)
  override fun writeTo(sink: BufferedSink) {
    delegate.writeTo(sink)
  }

  override fun isDuplex(): Boolean {
    return delegate.isDuplex()
  }

  override fun toString(): String {
    return javaClass.simpleName + "(" + delegate.toString() + ")"

 *
 * Unlike [okhttp3.ResponseBody], this interface is designed to be implemented by writers and not
 * called by readers.
 */
@ExperimentalOkHttpApi
interface MockResponseBody {
  /** The length of this response in bytes, or -1 if unknown. */
  val contentLength: Long

  @Throws(IOException::class)
  fun writeTo(sink: BufferedSink)