public void testReturning() throws Exception {
    assertNull(Callables.returning(null).call());

    Object value = new Object();
    Callable<Object> callable = Callables.returning(value);
    assertSame(value, callable.call());
    // Expect the same value on subsequent calls
    assertSame(value, callable.call());
  }

  @J2ktIncompatible
  @GwtIncompatible
  public void testAsAsyncCallable() throws Exception {

    server.requestClientAuth()
    server.enqueue(
      MockResponse
        .Builder()
        .body("abc")
        .build(),
    )
    val call = client.newCall(Request.Builder().url(server.url("/")).build())
    val response = call.execute()
    assertThat(response.handshake!!.peerPrincipal)
      .isEqualTo(X500Principal("CN=Local Host"))
    assertThat(response.handshake!!.localPrincipal)

  @ValueSource(booleans = [true, false])
  fun successfulCallEventSequence() {
    server!!.enqueue(MockResponse(body = "abc"))
    val call =
      client.newCall(
        Request
          .Builder()
          .url(server!!.url("/"))
          .build(),
      )
    val response = call.execute()
    assertThat(response.code).isEqualTo(200)
    assertThat(response.body.string()).isEqualTo("abc")
    response.body.close()

        .setSocketPolicy(SocketPolicy.STALL_SOCKET_AT_START),
    )
    server.start()
    val call =
      client.newCall(
        Request
          .Builder()
          .url(server.url("/"))
          .build(),
      )
    call.enqueue(
      object : Callback {
        override fun onFailure(
          call: Call,
          e: okio.IOException,
        ) {
          callFailure.complete(e)
        }

     *     {@link #whenAllComplete(Iterable)} or {@link #whenAllComplete(Iterable)}
     * @throws IllegalStateException if called outside of a call to {@link
     *     CombiningCallable#call(DeferredCloser, Peeker)} or {@link
     *     AsyncCombiningCallable#call(DeferredCloser, Peeker)}
     */
    @ParametricNullness
    public final <D extends @Nullable Object> D getDone(ClosingFuture<D> closingFuture)

        .build()
    val latch = CountDownLatch(1)
    val exceptionRef = AtomicReference<Throwable>()
    val call = client.newCall(request)
    call.timeout().timeout(250, TimeUnit.MILLISECONDS)
    call.enqueue(
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          exceptionRef.set(e)
          latch.countDown()
        }

        .trailersDelay(1, TimeUnit.SECONDS)
        .build(),
    )

    val call = client.newCall(Request(server.url("/")))
    call.execute().use { response ->
      val source = response.body.source()
      assertThat(response.header("h1")).isEqualTo("v1")
      assertThat(source.readUtf8(5)).isEqualTo("Hello")
      call.cancelLater(500.milliseconds)
      val trailersDelay =
        measureTime {

        override fun requestHeadersEnd(
          call: Call,
          request: Request,
        ) = TODO()

        override fun requestBodyStart(call: Call) = TODO()

        override fun requestBodyEnd(
          call: Call,
          byteCount: Long,
        ) = TODO()

        override fun requestFailed(
          call: Call,
          ioe: IOException,

    join();

    if (uncaughtThrowable != null) {
      throw new AssertionError("Uncaught throwable in " + getName(), uncaughtThrowable);
    }
  }

  /**
   * Causes this thread to call the named void method, and asserts that the call returns normally.
   */
  public void callAndAssertReturns(String methodName, Object... arguments) throws Exception {
    checkNotNull(methodName);
    checkNotNull(arguments);

  }

  /**
   * Cancel all calls currently enqueued or executing. Includes calls executed both
   * [synchronously][Call.execute] and [asynchronously][Call.enqueue].
   */
  @Synchronized
  fun cancelAll() {
    for (call in readyAsyncCalls) {
      call.call.cancel()
    }
    for (call in runningAsyncCalls) {
      call.call.cancel()
    }
    for (call in runningSyncCalls) {
      call.cancel()