Akka.Streams.Tests.Dsl.FlowConflateSpec.Conflate_must_backpressure_subscriber_when_upstream_is_slower C# (CSharp) Method

        public void Conflate_must_backpressure_subscriber_when_upstream_is_slower()
        {
            var publisher = TestPublisher.CreateProbe<int>(this);
            var subscriber = TestSubscriber.CreateManualProbe<int>(this);

            Source.FromPublisher(publisher)
                .ConflateWithSeed(i=>i, (sum, i) => sum + i)
                .To(Sink.FromSubscriber(subscriber))
                .Run(Materializer);
            var sub = subscriber.ExpectSubscription();

            sub.Request(1);
            publisher.SendNext(1);
            subscriber.ExpectNext(1);

            sub.Request(1);
            subscriber.ExpectNoMsg(TimeSpan.FromMilliseconds(500));
            publisher.SendNext(2);
            subscriber.ExpectNext(2);

            publisher.SendNext(3);
            publisher.SendNext(4);
            // The request can be in race with the above onNext(4) so the result would be either 3 or 7.
            subscriber.ExpectNoMsg(TimeSpan.FromMilliseconds(500));
            sub.Request(1);
            subscriber.ExpectNext(7);

            sub.Request(1);
            subscriber.ExpectNoMsg(TimeSpan.FromMilliseconds(500));
            sub.Cancel();
        }