Unit Testing Mediators

Does anyone test mediators? I've been running into a specific problem, that I hope you can help me with.

I have been trying to create a mock view component that I can use to send an event to the mediator that I'm testing. In the TestCase, I register the mediator with the facade like so:

var mockAddressForm:MockAddressForm = new MockAddressForm;
facade.registerMediator(new AddressMediator(mockAddressForm));

I've been following the standard pattern of creating mediators that have a getter method that returns the view component. So the mediator that I'm trying to test (AddressMediator) has the following constructor and getter method:

public function AddressMediator( viewComponent:Object ) {
super( NAME, viewComponent );

// Add the events we want to hear from the viewComponent
viewComponent.addEventListener( AddressForm.SAVE, onSave);
}

// Cast the viewComponent as the appropriate mxml component so we can reference it.
private function get addressForm():AddressForm{
return viewComponent as AddressForm;
}

The problem is that when the addressMediator makes reference to the viewComponent, it does so through the above getter. The mock object that I have created is not the same class as the actual viewComponent. So when this code in the mediator is called:

private function onSave( event:Event ):void {
sendNotification(ApplicationFacade.SAVE_STUFF, addressForm.stuff);
}

The addressForm getter returns null. I'm assuming this is because of the mismatch in packages, which makes sense. But that begs the question, what does everyone else do to test a mediator?

A whole other question is, is it worth the effort?

Thanks for your help!

jdp