Akka.Streams.Tests.Dsl.SourceSpec.Maybe_Source_must_allow_external_triggering_of_empty_completion C# (CSharp) Method

        public void Maybe_Source_must_allow_external_triggering_of_empty_completion()
        {
            this.AssertAllStagesStopped(() =>
            {
                var neverSource = Source.Maybe<int>().Where(_ => false);
                var counterSink = Sink.Aggregate<int, int>(0, (acc, _) => acc + 1);

                var t = neverSource.ToMaterialized(counterSink, Keep.Both).Run(Materializer);
                var neverPromise = t.Item1;
                var counterFuture = t.Item2;
                
                //external cancellation
                neverPromise.TrySetResult(0).Should().BeTrue();

                counterFuture.Wait(500).Should().BeTrue();
                counterFuture.Result.Should().Be(0);
            }, Materializer);
        }