public void DetectErrors(string label)
        {
            var s = new TestScheduler();
            var i = InvalidSequences[label];

            var a = s.LetRun(() => Observable.Return(i, s).DefragmentData());

            Assert.IsTrue(Dbg.Errored(a.Messages), Dbg.Show(a));
        }
        public void DetectErrorStates(string label)
        {
            var s = new TestScheduler();
            var i = s.EvenlySpacedHot(10, 10, BadInput[label]);

            var a = s.LetRun(() => Perf.MapToFrame(i));

            var r = Dbg.Errored(a.Messages);

            Assert.IsTrue(r, $"\n{Dbg.Show(a)}");
        }
 static string ShowError(ITestableObserver <WSFrame> fs) => Dbg.Errored(fs.Messages)
     ? fs.Messages.Select(x => x.Value?.Exception?.Message ?? "").Single()
     : Dbg.Show(fs);