def assertIn(self, member, container, msg=None):
        if member not in container:
            standardMsg = '%s not found in %s' % (safe_repr(member),
                                                   safe_repr(container))
            self.fail(self._formatMessage(msg, standardMsg))
Just like self.assertTrue(a in b), but with a nicer default message.
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.3/django/utils/unittest/case.py/TestCase.assertIn