Create test cases from generators

[rileyshahar]

It would be very convenient to create many test cases simultaneously from iterators. Here's an idea for an API:

test_cases(*args, aga_output = None, aga_product = True, aga_squash = False, **kwargs)

The user provides an iterator for each of the *args.

• If aga_product is true, we create one set of test inputs for each element of the Cartesian product of each iterator. Otherwise, we iterate through each iterator simultaneously, creating one set of test inputs for each iteration, and stopping (or erroring?) if their lengths differ.
• If aga_squash is False, we create one test case for each set of test inputs; otherwise, we put them all in a single test case, and have that test case loop through each set of inputs.
• aga_output (and any other aga_-prefixed kwargs) is passed directly to test_case. It should also be a generator and probably only makes sense if aga_product is False, or maybe we just don't want to allow parameterized golden tests like this.