public void SelectMany_ArgumentChecking() { var ns = default(ISubscribable <int>); var xs = DummySubscribable <int> .Instance; ReactiveAssert.Throws <ArgumentNullException>(() => Subscribable.SelectMany(ns, _ => xs)); ReactiveAssert.Throws <ArgumentNullException>(() => Subscribable.SelectMany(xs, default(Func <int, ISubscribable <string> >))); ReactiveAssert.Throws <ArgumentNullException>(() => Subscribable.SelectMany(ns, _ => xs, (x, y) => x + y)); ReactiveAssert.Throws <ArgumentNullException>(() => Subscribable.SelectMany(xs, default(Func <int, ISubscribable <string> >), (x, y) => x + y)); ReactiveAssert.Throws <ArgumentNullException>(() => Subscribable.SelectMany(xs, _ => xs, default(Func <int, int, int>))); }