I'm trying to do tests on libraries that work with the RC subsystem.

One of the problems I'm facing is that it is difficult to mock it - once bob.extension is imported, the contents of the RC file is loaded and there seems to be no easy way to affect such a value in a cross-module way.

Ideally, what you'd like to do is something like this:

@mock_bobs_rc('var1', 'override-value1')
def test():
   # now, code that uses bob.extension.rc will use the mock value
   # notice that the code is not necessarily here, but may be used several layers down

Can you think of an easy solution to this?