public void CanUnregisterSubscriberByKey()
        {
            Assume.That(_bus.HasSubscriptionFor <TestEvent>(), Is.False, "Expected the bus to not have any subscriptions for TestEvent");

            var events = new EventSubscribers();

            _bus.RegisterSubscriptionFor <TestEvent>("Key1", events.Handle);
            _bus.RegisterSubscriptionFor <TestEvent>("Key2", events.Handle);

            Assume.That(_bus.HasSubscription("Key1"), Is.True, "Expected a subscriber registered with key: Key1");
            Assume.That(_bus.HasSubscription("Key2"), Is.True, "Expected a subscriber registered with key: Key2");

            _bus.UnRegisterSubscription("Key1");

            Assert.That(_bus.HasSubscription("Key1"), Is.False);
            Assert.That(_bus.HasSubscription("Key2"), Is.True);
        }