public void UseObserverTest2() { var subject = new Subject<string>(); var result = new List<string>(); subject .UseObserver((observer, value, i) => { observer.OnNext(value); }, (error, observer) => { observer.OnNext(error.Message); }, observer => { observer.OnNext("end"); }) .Subscribe(result.Add); subject.OnNext("a"); subject.OnError(new Exception("error!")); subject.OnCompleted(); result.Is("a", "error!"); }