The problem is that Woody components (like for instance AbstractDatatypeWidgetDefinition) are Serviceable, but ExcaliburTestCase provides only a (deprecated) ComponentManager instead of a ServiceManager.
I don't know if this will help you, but I've been experimenting with using the CocoonBean in my test cases. You could create a subclass of the CocoonBean class that will expose the getComponentManager() method to your test case. You could then use that method to create and test the component.
cheers, -steve
