* ### 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

    @Throws(IOException::class)
    override fun writeTo(sink: BufferedSink) {
      val forwardingSink =
        object : ForwardingSink(sink) {
          private var totalBytesWritten: Long = 0
          private var completed = false

          override fun write(
            source: Buffer,
            byteCount: Long,
          ) {
            super.write(source, byteCount)
            totalBytesWritten += byteCount

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

  @Test
  fun streamingPartHasNoLength() {
    class StreamingBody(
      private val body: String,
    ) : RequestBody() {
      override fun contentType(): MediaType? = null

      @Throws(IOException::class)
      override fun writeTo(sink: BufferedSink) {
        sink.writeUtf8(body)

    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,
        )
      }
    }

    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() {

  @Throws(IOException::class)
  override fun contentLength(): Long = delegate.contentLength()

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

  override fun isDuplex(): Boolean = delegate.isDuplex()

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

  init {

            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)

) : RequestBody() {
  override fun contentType() = delegate.contentType()

  // We don't know the compressed length in advance!
  override fun contentLength() = -1L

  override fun writeTo(sink: BufferedSink) {
    GzipSink(sink).buffer().use(delegate::writeTo)
  }

  override fun isOneShot() = delegate.isOneShot()

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

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