Following some discussion on the Laravel Doctrine Slack I've made this as an example of two ways I can think of of dispatching domain events from the model.
In both types we have a simple User which wants to raise an event (UserNameWasChanged) when its name changes.
In EventsExample\DispatchesImmediately the User dispatches events directly, using a static dispatcher, which simply
wraps a real dispatcher.
We can test events by assigning a mock dispatcher to our wrapping class.
Pros:
- We know that Events will get properly dispatched (or the application will fail hard)
Cons:
- Events are dispatched as soon as they happen, might not be desire able if we immediately roll them back / throw away our changed objects
In EventsExample\DispatchesLater the User simply holds a collection of events itself, and waits for something
external to ask for what has happened to it, this could be an ORM, a command, a controller etc.
We test events by checking that the correct type is held against the user object.
Pros:
- We have control over when the events are dispatched
Cons:
- We are reliant on something outside the domain model actually firing our events for us.