ArgumentCaptor<AllServiceListener> argument = ArgumentCaptor.forClass(AllServiceListener.class);
verify(context).addServiceListener(argument.capture());
//send events
AllServiceListener serviceListener = argument.getValue();
serviceListener.serviceChanged(registeredEvent);
serviceListener.serviceChanged(modifiedEvent);
//shutdown dispatcher via unregister callback
serviceState.postDeregister();
//check the ServiceListener is cleaned up