setupClass called for every test if class is not a subclass of TestCase

[MLModel]

In a test class with no superclasses setUpClass is executed once for every test. If the class is a subclass of TestCase it is executed only once then the tests are executed.

[katrinabrock]

@little-dude is this expected behavior? If so, maybe should be better documented. Even if this is not intended behavior, I'm guessing other users probably rely on it so probably a won't fix, but please weigh in.