public void DelaySubscription_ArgumentChecking()
{
ReactiveAssert.Throws <ArgumentNullException>(() => Subscribable.DelaySubscription(default(ISubscribable <int>), DateTimeOffset.Now));
ReactiveAssert.Throws <ArgumentNullException>(() => Subscribable.DelaySubscription(default(ISubscribable <int>), TimeSpan.Zero));
ReactiveAssert.Throws <ArgumentOutOfRangeException>(() => Subscribable.DelaySubscription(DummySubscribable <int> .Instance, TimeSpan.FromSeconds(-1)));
}