public void InitialTimeout_must_fail_if_no_initial_element_passes_until_timeout()
{
this.AssertAllStagesStopped(() =>
{
var downstreamProbe = this.CreateProbe<int>();
Source.Maybe<int>()
.InitialTimeout(TimeSpan.FromSeconds(1))
.RunWith(Sink.FromSubscriber(downstreamProbe), Materializer);
downstreamProbe.ExpectSubscription();
downstreamProbe.ExpectNoMsg(TimeSpan.FromMilliseconds(500));
var ex = downstreamProbe.ExpectError();
ex.Message.Should().Be($"The first element has not yet passed through in {TimeSpan.FromSeconds(1)}.");
}, Materializer);
}