Great post!

Whenever I want to unit test the post controller it fails in the init() method of the MyApp class because the session is not instantiated:
AttributeError: 'thread._local' object has no attribute 'session'

So what is the correct way of testing the controller/action? How should I mock the post handler object?

I come from the .NET world in which with IoC/DI, you can mock the dependency of the controller (the handler, in this case) and pass it to the controller/action as a parameter.
But in this case in which the handler is instantiated inside the controller/action, how can that be done? Or should I mock the session, request and response objects themselves?

Thanks!