public void Expand_ArgumentChecking()
{
ReactiveAssert.Throws <ArgumentNullException>(() => ObservableEx.Expand(null, DummyFunc <int, IObservable <int> > .Instance, DummyScheduler.Instance));
ReactiveAssert.Throws <ArgumentNullException>(() => ObservableEx.Expand(DummyObservable <int> .Instance, null, DummyScheduler.Instance));
ReactiveAssert.Throws <ArgumentNullException>(() => ObservableEx.Expand(DummyObservable <int> .Instance, DummyFunc <int, IObservable <int> > .Instance, null));
ReactiveAssert.Throws <ArgumentNullException>(() => ObservableEx.Expand(null, DummyFunc <int, IObservable <int> > .Instance));
ReactiveAssert.Throws <ArgumentNullException>(() => ObservableEx.Expand(DummyObservable <int> .Instance, null));
}