Akka.Streams.Tests.Dsl.FlowGroupBySpec.GroupBy_must_fail_when_exceeding_maxSubstreams C# (CSharp) Метод

        public void GroupBy_must_fail_when_exceeding_maxSubstreams()
        {
            this.AssertAllStagesStopped(() =>
            {
                var f = Flow.Create<int>().GroupBy(1, x => x%2).PrefixAndTail(0).MergeSubstreams();
                var t = ((Flow<int, Tuple<IImmutableList<int>, Source<int, NotUsed>>, NotUsed>) f)
                    .RunWith(TestSource.SourceProbe<int>(this), TestSink.SinkProbe<Tuple<IImmutableList<int>, Source<int, NotUsed>>>(this), Materializer);
                var up = t.Item1;
                var down = t.Item2;

                down.Request(2);

                up.SendNext(1);
                var first = down.ExpectNext();
                var s1 = new StreamPuppet(first.Item2.RunWith(Sink.AsPublisher<int>(false), Materializer), this);

                s1.Request(1);
                s1.ExpectNext(1);

                up.SendNext(2);
                var ex = down.ExpectError();
                ex.Message.Should().Contain("too many substreams");
                s1.ExpectError(ex);
            }, Materializer);
        }
    }