How can I test a table of options with python unittest and nosetests?

Question

I have a list of twelve properties and want to test various combinations. The actual test function is the same, just different parameters. I find myself writing a bunch of functions that look like this:

def test_paramA(self): self.with_params("A")
def test_paramA_B(self): self.with_params("A+B")
def test_paramA_C(self): self.with_params("A+C")
def test_paramB_C(self): self.with_params("B+C")

I'd like to instead write this:

combinations = ["A", "A+B", "A+C", "B+C"]
combinationSuite = (make_test_function(c) for c in combinations)

Is there any way to make my test driver (nosetests) run all the tests in combinationSuite? Do I need a custom test collector?

Answer 1

Nose supports parametric/generative tests, http://readthedocs.org/docs/nose/en/latest/writing_tests.html#test-generators

For example:

def checker(combination):
    # do something to verify the combination 
    assert 'A' in combination

def test_generator():
    options = ['A', 'B', 'C']
    for o in options:
        yield checker, o

    for p in itertools.permutations(options, 2):
        yield checker, p

9 tests are created by nose and results in 4 failures, which would be expected. Also, beware that generative tests do not work with unittest.TestCase subclasses.