public void Publish_WhenEventParameterNotNull_AndSubscriberIsDeregistered_SubscriberIsNotNotified() { _aggregator.RegisterTo(_subscriberStub.Object); _aggregator.DeregisterFrom(_subscriberStub.Object); _aggregator.Publish(new Event()); _subscriberStub.Verify( ss => ss.ReceiveEventAsync(It.IsAny <Event>()), Times.Never); }