Example for https://twitter.com/camillereynders/status/241116901382713345

BaseService.as

class BaseService{
	public function load():void{
		this.onLoadComplete()
	}

	public function onLoadComplete():void{

	}
}

BaseServiceTest.as

class BaseServiceTest{
    public var instance : BaseService;

    [Test]
    public function test_load_callsOnLoadComplete():void{
        instance.load();
        //how to test onLoadComplete was called?
    }
}

ConcreteService.as

class ConcreteService extends EventDispatcher{
    override public function onLoadComplete():void{
        dispatchEvent( new ConcreteServiceEvent( ConcreteServiceEvent.LOAD_COMPLETE ) );
    }
}