bdd ext + RhinoMocks.Do()

public class LightSwitchedOff : IBehaviorConfig {

	public void EstablishContext(IDependencyAccessor accessor) {
			
		accessor.The<ILight>().WhenToldTo(l => l.LightState).Return(LightState.Off).Repeat.Once();
		accessor.The<ILight>().WhenToldTo
			(l => l.SwitchLight(LightState.On)).Do(
					new Func<object, LightSwitchedHandlerArgs, int>((sender1, args1) => 
						{
			                accessor.The<ILight>()
								.Event(l => l.LightSwitched += (sender, args) => { })
								.Raise(this, new { LightState.On });
			                return 0;
			            }));
	}

	public void PrepareSut(object sut) {
	}

	public void Cleanup(object sut) {
	}
}

Where:

public delegate void LightSwitchedHandler(object sender, LightSwitchedHandlerArgs args);

and:

public LightSwitchedHandlerArgs(LightState lightState)