metaclasses_at_work.py

import unittest

def foo(x, y, z):
    return (x != y and x != z or x and z)

def get_test_args():
    x = y = z = [True, False]
    from itertools import product, repeat
    # for each input arg ---> expected arg
    input_args = list(product(x, y, z))
    expected_args = [
        True,
        False,
        True,
        True,
        True,
        False,
        True,
        False]

    test_names = list(range(1, len(expected_args) + 1))
    for test_name, i, e in zip(test_names, input_args, expected_args):
        yield (str(test_name), i, e)


class TestFunctionFooMeta(type):
    def __new__(cls, name, bases, attrs):
        # factory method to create each test method
        def create_func(test_name, input_args, expected_args):
            def func(self):
                result = foo(*input_args)   # call the Function under test
                self.check_common_invariants(result, expected_args)
            func.__name__ = "test_" + str(test_name)
            return func

        # get_test_args yields (test_name, input_args, expected_value)
        for test_name, input_args, expected_args in get_test_args():
            func = create_func(test_name, input_args, expected_args)
            attrs[func.__name__] = func
        return type.__new__(cls, name, bases, attrs)


class TestUnit(unittest.TestCase, metaclass=TestFunctionFooMeta):

    def check_common_invariants(self, actual_value, expected_value):
        self.assertEqual(actual_value, expected_value)


if __name__ == '__main__':
    unittest.main()