public void A_FLow_with_a_Sink_Head_must_yield_the_first_value()
{
this.AssertAllStagesStopped(() =>
{
var p = TestPublisher.CreateManualProbe<int>(this);
var task = Source.FromPublisher(p).Select(x=>x).RunWith(Sink.First<int>(), Materializer);
var proc = p.ExpectSubscription();
proc.ExpectRequest();
proc.SendNext(42);
task.Wait(100);
task.Result.Should().Be(42);
proc.ExpectCancellation();
}, Materializer);
}