Akka.Streams.TestKit.Tests.TestPublisherSubscriberSpec.TestPublisher_and_TestSubscriber_should_have_all_events_accessible_from_manual_probes C# (CSharp) Method

        public void TestPublisher_and_TestSubscriber_should_have_all_events_accessible_from_manual_probes()
        {
            this.AssertAllStagesStopped(() =>
            {
                var upstream = TestPublisher.CreateManualProbe<int>(this);
                var downstream = TestSubscriber.CreateManualProbe<int>(this);
                Source.FromPublisher(upstream)
                    .RunWith(Sink.AsPublisher<int>(false), Materializer)
                    .Subscribe(downstream);

                var upstreamSubscription = upstream.ExpectSubscription();
                object evt = downstream.ExpectEvent();
                evt.Should().BeOfType<TestSubscriber.OnSubscribe>();
                var downstreamSubscription = ((TestSubscriber.OnSubscribe) evt).Subscription;

                upstreamSubscription.SendNext(1);
                downstreamSubscription.Request(1);
                evt = upstream.ExpectEvent();
                evt.Should().BeOfType<TestPublisher.RequestMore>();
                ((TestPublisher.RequestMore) evt).NrOfElements.Should().Be(1);
                evt = downstream.ExpectEvent();
                evt.Should().BeOfType<TestSubscriber.OnNext<int>>();
                ((TestSubscriber.OnNext<int>) evt).Element.Should().Be(1);

                upstreamSubscription.SendNext(1);
                downstreamSubscription.Request(1);
                downstream.ExpectNext(1);

                upstreamSubscription.SendComplete();
                evt = downstream.ExpectEvent();
                evt.Should().BeOfType<TestSubscriber.OnComplete>();
            }, Materializer);
        }