'Verify that any not expected field name in the post-back is not stored
in the database'

def test_strip_extra_fields(self):

    data = dict.copy(self.student_answers)
    data['csrfmiddlewaretoken'] = 'foo'
    data['_redirect_url'] = 'bar'
    data['course_id'] = unicode(self.course.id)
    resp = self.client.post(self.postback_url, data)
    self.assertEquals(resp.status_code, 200)
    answers = self.survey.get_answers(self.student)
    self.assertNotIn('csrfmiddlewaretoken', answers[self.student.id])
    self.assertNotIn('_redirect_url', answers[self.student.id])
    self.assertNotIn('course_id', answers[self.student.id])
    answer_objs = SurveyAnswer.objects.filter(user=self.student, form=self.survey)
    for answer_obj in answer_objs:
        self.assertEquals(unicode(answer_obj.course_key), data['course_id'])
