Running py.test tests using python -m (in PyCharm)

I have a feature I want to test using py.test but it requires that the package in which it sits is loaded [1]. Therefore the test needs to be run using "-m".

Is there a way of telling py.test to use python -m mypackage.mymodule to run these tests? I'm using the PyCharm IDE if that makes a difference.

[1] I'm aware this might seem like bad design but the feature is to do with package resources, hence there's no way of testing it outside of a package.