It all works now as far as i can see. I also like the abstraction into a class in lang of the SoftReference.
I am afraid that applicationDomains are read-only... So you'll have to load a module to test. But i understand you want a unit test and not an integration test. I was recently looking at mocking and unit testing in flex. The next stuff looks good:
I wonder if you can Mock an applicationDomain... On the other hand, why not? Anyway this doesn't look like a usual case and i personally would go for the integration test... Looks easier.
Have a good weekend and thank u very much!