Adding test methods dynamically using decorator

Question

I've been using DDT to parameterize my tests with great success for the past few months. My issue now is that I can't seem to inject a list variable as my data source. Doing so seems to confuse DDT causing it to not parameterize my tests. I started to create my own solution, but I can't seem to figure this last part out.

Here is what I have thus far as decorators -

def data(*values):
    def aaa(func):
        def wrapper(self, *args, **kwargs):
            pass
#             return func(self, *args, **kwargs)
        wrapper.func_name = func.__name__ + 't'
        wrapper.values = values
        return wrapper
    return aaa


def c(cls):
    for name, method in list(cls.__dict__.items()):
        if hasattr(method, 'values'):
            for ticket in method.values[0]:
                test_name = mk_test_name(method.func_name, ticket)
                print(test_name)
                setattr(cls, test_name, method(cls, ticket))
    return cls

And I use it as such -

@c
class IntegrationTests(APITestCase):
    tickets = [1, 2, 3, 4]

    @data(tickets)
    def tes(self, t):
        print(t)

How can I make the Python testing framework recognize that I've added via decorator? I know the methods have been added because issuing the dir command in PDB displays them. The goal for this is that I would duplicate the test(s) I decorate for each item in a list. For those wondering why wrapper() has no code, I did this because uncommenting the line the return call causes the method I decorate to be executed without parameters, thus causing an error.

In my example, I would expect 4 tests with different names to be executed.

Answer 1

The best solution is to use the sub tests feature of unittest in python 3.4. Documentation found here and used like:

class NumbersTest(unittest.TestCase):

    def test_even(self):
        """
        Test that numbers between 0 and 5 are all even.
        """
        for i in range(0, 6):
            with self.subTest(i=i):
                self.assertEqual(i % 2, 0)

For those who cannot use python 3.4, the following is a poor man's replacement.

class sub_test_data(object):

    def __init__(self, *test_data):
        self.test_data = test_data

    def __call__(self, func):
        func.sub_test_data = self.test_data
        func.has_sub_tests = True
        return func

def create_test_driver(func, *args):
    def test_driver(self):
        try:
            func(self, *args)
        except AssertionError as e:
            e.args += ({"test_args": args},)
            raise
    return test_driver  

def create_sub_tests(cls):
    for attr_name, func in list(vars(cls).items()):
        if getattr(func, "has_sub_tests", False):
            for i, value in enumerate(func.sub_test_data):
                test_name = 'test_{}_subtest{}'.format(attr_name, i)
                setattr(cls, test_name, create_test_driver(func, value))
    return cls

@create_sub_tests
class NumbersTest(unittest.TestCase):
    tickets = [0, 1, 2, 3, 4, 5]

    @sub_test_data(*tickets)
    def even(self, t):
        self.assertEqual(t % 2, 0)