'An assertion is raised if the formset name is unknown'

def test_unknown_formset(self):

    for (prefix, kwargs) in self.msg_prefixes:
        with self.assertRaises(AssertionError) as cm:
            self.assertFormsetError(self.response_form_errors, u'wrong_formset', 0, u'Some_field', u'Some    error.', **kwargs)
        self.assertIn((prefix + u"The    formset    'wrong_formset'    was    not    used    to    render    the    response"), str(cm.exception))
