how to run every unittest in a test suite individually?

I am using PyCharm to run a fairly sized test suite (1800 fast tests). Modifying a test recently, I realized my test would not break. The do break when I run those tests individually, but if I run the whole test suite they will always pass. This is due to this type of incorrect mocking of classes some previous co-workers did:

import script

script.aClass = Mock()

I now need to check the usage of mocks in the whole test suite, but I would like to run every test individually and see which are the ones that are not passing (I will mark those as high priority). How can I do this either from a console or from Pycharm?