required_spec208_mustBePreparedToReceiveOnNextSignalsAfterHavingCalledSubscriptionCancel does not wait for request before invoking onNext

[jroper]

  @Override @Test
  public void required_spec208_mustBePreparedToReceiveOnNextSignalsAfterHavingCalledSubscriptionCancel() throws Throwable {
    subscriberTest(new TestStageTestRun() {
      @Override
      public void run(WhiteboxTestStage stage) throws InterruptedException {
        stage.puppet().triggerRequest(1);
        stage.puppet().signalCancel();
        stage.signalNext();

        stage.puppet().triggerRequest(1);
        stage.puppet().triggerRequest(1);

        stage.verifyNoAsyncErrors();
      }
    });
  }

Note, it triggers the request, but then does not wait for the request to arrive at the subscription before signalling next. This violates the spec, and is causing my tests to fail, since my subscriber setup and request triggering is asynchronous, so my subscriber under test is not necessarily ready to receive elements before requesting them.

[jroper]

required_spec308_requestMustRegisterGivenNumberElementsToBeProduced also has the same problem:

  public void required_spec308_requestMustRegisterGivenNumberElementsToBeProduced() throws Throwable {
    subscriberTest(new TestStageTestRun() {
      @Override
      public void run(WhiteboxTestStage stage) throws InterruptedException {
        stage.puppet().triggerRequest(2);
        stage.probe.expectNext(stage.signalNext());
        stage.probe.expectNext(stage.signalNext());

        stage.probe.expectNone();
        stage.puppet().triggerRequest(3);

        stage.verifyNoAsyncErrors();
      }
    });
  }

[ktoso]

Thanks for reporting James! What you observe indeed looks wrong, I'll give it a look today evening.

[jroper]

Here's an instance of the TCK failing against Akka Streams due to this bug:

akka/akka#25927