We've been using Udi Dahan's excellent Domain Events pattern in a project at work. It's best to keep them as coarse-grained as possible, but we have already identified a dozen or so events that need to be raised by the domain and processed by our services layer.
Naturally, however, I am forgetting to register some of the event handlers in our IoC container. So, as before with our domain services, I decided to write some integration tests to check everything is set up properly. This is very simple to achieve using NUnit's trusty parameterized tests, ServiceLocator and a sprinkling of generics:
This reveals a nice todo list of all the handlers we haven't implemented yet. And the ones I forgot to register!