val responseA = client.newCall(requestA).execute()
              assertThat(responseA.body.string()).isEqualTo("a")
            }
            chain.proceed(chain.request())
          },
        )
        .build()
    val requestB =
      Request.Builder()
        .url(server.url("/b"))
        .build()
    val responseB = client.newCall(requestB).execute()
    assertThat(responseB.body.string()).isEqualTo("b")

      }
    }

    override fun <T> decorate(queue: BlockingQueue<T>) = queue

    override fun execute(
      taskRunner: TaskRunner,
      runnable: Runnable,
    ) {
      executor.execute(runnable)
    }

    fun shutdown() {
      executor.shutdown()
    }
  }

  companion object {
    val logger: Logger = Logger.getLogger(TaskRunner::class.java.name)

      MockResponse(body = "unexpected call to IPv4"),
    )
    serverIpv6.enqueue(
      MockResponse(body = "hello from IPv6"),
    )

    val call = client.newCall(Request(url))
    val response = call.execute()
    assertThat(response.body.string()).isEqualTo("hello from IPv6")

    // In the process we made one successful connection attempt.
    assertThat(listener.recordedEventTypes().filter { it == "ConnectStart" }).hasSize(1)

        .post(sleepingRequestBody(500))
        .build()
    val call = client.newCall(request)
    call.timeout().timeout(250, TimeUnit.MILLISECONDS)
    assertFailsWith<IOException> {
      call.execute()
    }.also { expected ->
      assertThat(expected.message).isEqualTo("timeout")
      assertThat(call.isCanceled()).isTrue()
    }
  }

  @Test
  fun timeoutWritingRequestWithEnqueue() {

    server.enqueue(MockResponse())
    assert200Http2Response(execute(url), server.hostName)
    val sanUrl = url.newBuilder().host("san.com").build()
    assert200Http2Response(execute(sanUrl), "san.com")
    assertThat(client.connectionPool.connectionCount()).isEqualTo(2)
  }

  private fun execute(url: HttpUrl) = client.newCall(Request(url = url)).execute()

  private fun assert200Http2Response(
    response: Response,

    val call =
      client.newCall(
        Request.Builder()
          .url(server.url("/"))
          .post(AsyncRequestBody())
          .build(),
      )
    assertFailsWith<ProtocolException> {
      call.execute()
    }
  }

  @Test
  fun trueDuplexClientWritesFirst() {
    enableProtocol(Protocol.HTTP_2)
    val body =
      MockStreamHandler()
        .receiveRequest("request A\n")

  /** Guarded by [TaskRunner.lock]. */
  private var activeThreads = 0

  /** A task runner that posts tasks to this fake. Tasks won't be executed until requested. */
  val taskRunner: TaskRunner =
    TaskRunner(
      object : TaskRunner.Backend {
        override fun execute(
          taskRunner: TaskRunner,
          runnable: Runnable,
        ) {
          taskRunner.assertThreadHoldsLock()

    server.enqueue(MockResponse(body = "b"))
    val request = Request(server.url("/"))
    val responseA = client.newCall(request).execute()
    assertThat(responseA.body.string()).isEqualTo("a")
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)
    val responseB = client.newCall(request).execute()
    assertThat(responseB.body.string()).isEqualTo("b")
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(1)

  @Test fun singleQueueIsSerial() {
    redQueue.execute("task one", 100.µs) {
      log += "one:run@${taskFaker.nanoTime} parallel=${taskFaker.isParallel}"
    }

    redQueue.execute("task two", 100.µs) {
      log += "two:run@${taskFaker.nanoTime} parallel=${taskFaker.isParallel}"
    }

    redQueue.execute("task three", 100.µs) {

    val request = Request.Builder().url(server.url("/")).build()

    client.newCall(request).execute().use { response ->
      assertEquals(200, response.code)
    }

    client.connectionPool.evictAll()
    assertEquals(0, client.connectionPool.connectionCount())

    client.newCall(request).execute().use { response ->
      assertEquals(200, response.code)
    }

    assertEquals(2, sessionIds.size)