server!!.enqueue(MockResponse())
    server!!.enqueue(MockResponse())

    client.newCall(Request(server!!.url("/")))
      .execute().close()

    client.newCall(Request(server!!.url("/")))
      .execute().close()

    assertThat(listener.recordedEventTypes()).containsExactly(
      "ConnectStart",
      "ConnectEnd",
      "ConnectionAcquired",
      "ConnectionReleased",

    val call = client.newCall(Request(serverRule.server.url("/")))

    call.execute().use { response ->
      assertThat(response.code).isEqualTo(200)
    }
  }

  @Test
  fun testRequestExternal() {
    assumeNetwork()

    val call = client.newCall(Request("https://google.com/robots.txt".toHttpUrl()))

    call.execute().use { response ->
      assertThat(response.code).isEqualTo(200)
    }
  }

programs that TensorFlow executes. TensorFlow programs are encoded as
computation
[**graphs**](https://developers.google.com/machine-learning/glossary/#graph).
Since models are practically programs that TensorFlow executes, using untrusted
models or graphs is equivalent to running untrusted code.

If you need to run untrusted models, execute them inside a

    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) {

        .header("User-Agent", "SyncApiTest")
        .build()
    val call = client.newCall(request)
    val response = call.execute()
    response.body.close()
    assertFailsWith<IllegalStateException> {
      call.execute()
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Already Executed")
    }
    assertFailsWith<IllegalStateException> {
      call.enqueue(callback)
    }.also { expected ->

    val callB = client.newCall(Request(server.url("/")))
    callB.execute().use { response ->
      assertThat(response.body.string()).isEqualTo("abc")
    }
  }

  private fun makeSimpleCall() {
    server.enqueue(MockResponse(body = "healthy"))
    val callB = client.newCall(Request(server.url("/")))
    callB.execute().use { response ->
      assertThat(response.body.string()).isEqualTo("healthy")
    }