Akka.Streams.Tests.Actor.ActorSubscriberSpec.ActorSubscriber_should_receive_requested_elements C# (CSharp) Method

        public void ActorSubscriber_should_receive_requested_elements()
        {
            var actorRef = Source.From(new[] { 1, 2, 3 })
                    .RunWith(Sink.ActorSubscriber<int>(ManualSubscriber.Props(TestActor)), Sys.Materializer());

            ExpectNoMsg(200);
            actorRef.Tell("ready"); //requesting 2
            ExpectMsg<OnNext>().Element.Should().Be(1);
            ExpectMsg<OnNext>().Element.Should().Be(2);
            ExpectNoMsg(200);
            actorRef.Tell("ready");
            ExpectMsg<OnNext>().Element.Should().Be(3);
            ExpectMsg<OnComplete>();
        }