public void Empty_Source_must_complete_immediately()
{
var p = Source.Empty<int>().RunWith(Sink.AsPublisher<int>(false), Materializer);
var c = TestSubscriber.CreateManualProbe<int>(this);
p.Subscribe(c);
c.ExpectSubscriptionAndComplete();
//reject additional subscriber
var c2 = TestSubscriber.CreateManualProbe<int>(this);
p.Subscribe(c2);
c2.ExpectSubscriptionAndError();
}