public void Maybe_Source_must_complete_materialized_future_with_None_when_stream_cancels()
{
this.AssertAllStagesStopped(() =>
{
var neverSource = Source.Maybe<object>();
var pubSink = Sink.AsPublisher<object>(false);
var t = neverSource.ToMaterialized(pubSink, Keep.Both).Run(Materializer);
var f = t.Item1;
var neverPub = t.Item2;
var c = TestSubscriber.CreateManualProbe<object>(this);
neverPub.Subscribe(c);
var subs = c.ExpectSubscription();
subs.Request(1000);
c.ExpectNoMsg(TimeSpan.FromMilliseconds(300));
subs.Cancel();
f.Task.Wait(500).Should().BeTrue();
f.Task.Result.Should().Be(null);
}, Materializer);
}