Iterating over test data in unit tests

[Steven Bethard]

Ben Finney wrote:
> Maybe I need to factor out the iteration into a generic iteration
> function, taking the actual test as a function object. That way, the
> dataset iterator doesn't need to know about the test function, and
> vice versa.
> 
>         def iterate_test(self, test_func, test_params=None):
>             """ Iterate a test function for all the sets """
>             if not test_params:
>                 test_params = self.game_params
>             for key, params in test_params.items():
>                 dataset = params['dataset']
>                 instance = params['instance']
>                 test_func(key, dataset, instance)
> 
>         def test_score_throws(self):
>             """ Game score should be calculated from throws """
>             def test_func(key, dataset, instance):
>                 score = dataset['score']
>                 for throw in dataset['throws']:
>                     instance.add_throw(throw)
>                 self.failUnlessEqual(score, instance.get_score())
> 
>             self.iterate_test(test_func)
> 
> That's somewhat clearer; the test function actually focuses on what
> it's testing. Those layers of indirection are annoying, but they allow
> the data sets to grow without writing more code to handle them.

Don't know if this helps, but I'd be more likely to write this as 
something like (untested)::

     def get_tests(self, test_params=None):
         """ Iterate a test function for all the sets """
         if not test_params:
             test_params = self.game_params
         for key, params in test_params.items():
             dataset = params['dataset']
             instance = params['instance']
             yield key, dataset, instance

     def test_score_throws(self):
         """ Game score should be calculated from throws """
         for key, dataset, instance in self.get_tests()
             score = dataset['score']
             for throw in dataset['throws']:
                 instance.add_throw(throw)
             self.failUnlessEqual(score, instance.get_score())

That is, make an interator to the various test information, and just put 
your "test_func" code inside a for-loop.

STeVe