Akka.Streams.Tests.Dsl.QueueSinkSpec.QueueSink_should_work_with_one_element_buffer C# (CSharp) Method

        public void QueueSink_should_work_with_one_element_buffer()
        {
            this.AssertAllStagesStopped(() =>
            {
                var sink = Sink.Queue<int>().WithAttributes(Attributes.CreateInputBuffer(1, 1));
                var probe = TestPublisher.CreateManualProbe<int>(this);
                var queue = Source.FromPublisher(probe).RunWith(sink, _materializer);
                var sub = probe.ExpectSubscription();

                queue.PullAsync().PipeTo(TestActor);
                sub.SendNext(1); // should pull next element
                ExpectMsg(new Option<int>(1));

                queue.PullAsync().PipeTo(TestActor);
                ExpectNoMsg(); // element requested but buffer empty
                sub.SendNext(2);
                ExpectMsg(new Option<int>(2));

                sub.SendComplete();
                var future = queue.PullAsync();
                future.Wait(_pause).Should().BeTrue();
                future.Result.Should().Be(Option<int>.None);
            }, _materializer);
        }