Hey Lex,
To run the tests in PyCharms I followed the following steps:
1) In Run -> Edit Configurations, I created a new Configuration.
2) In the script field I gave the path to the runtests.py file and gave script parameter as one of the test files since I only wanted to run the tests present in one directory.
3) I gave the name as 'runtests'.
After applying the changes "Run 'runtests' " & "Debug 'runtests' " were available in the Run menu.
Hope that helps.