Launch Django tests in app subdirectories?

I have a django app that has models and tests in its subdirctories: e.g. /app/subclass/models.py and /app/subclass/tests/model_tests.py.  

In pycharm 2.x, I could right click on the tests and automatically launch them, but after upgrading to 3.x/4.x I can't automatically launch those tests without editing the run configuration and changing the test name from "subclass.MyModelTests" to "app.MyModelTests"  

Does anyone know a way of telling auto-launch that the tests belong to the app, and not the subclass of the app?

Thanks,
BruceW