public void A_ActorRefSource_must_buffer_when_needed()
{
var s = TestSubscriber.CreateManualProbe<int>(this);
var actorRef = Source.ActorRef<int>(100, OverflowStrategy.DropHead)
.To(Sink.FromSubscriber(s))
.Run(Materializer);
var sub = s.ExpectSubscription();
Enumerable.Range(1, 20).ForEach(x => actorRef.Tell(x));
sub.Request(10);
Enumerable.Range(1, 10).ForEach(x => s.ExpectNext(x));
sub.Request(10);
Enumerable.Range(11, 10).ForEach(x => s.ExpectNext(x));
Enumerable.Range(200, 200).ForEach(x => actorRef.Tell(x));
sub.Request(100);
Enumerable.Range(300, 100).ForEach(x => s.ExpectNext(x));
}