Question

I’d like to give the run method a default argument so that it will run all test cases if no test_cases argument is given. How would you recommend I do this?

from collections import OrderedDict
class TestCase(OrderedDict):
    def run(self, test_cases):
        for test_case_name in test_cases:
            self[test_case_name].run()

Answer 1

from collections import OrderedDict
class TestCase(OrderedDict):
    def run(self, test_cases=None):
        if test_cases is None:
            test_cases = default_all_test_cases # add all your default test cases here
        for test_case in test_cases:
            test_case.run()

You can replace the default None by another immutable object, such as string or integer.