'Helper function that posts to \'students_update_enrollment\' to change
a student\'s enrollment'

def _change_student_enrollment(self, user, course, action):

    url = reverse('students_update_enrollment', kwargs={'course_id': course.id.to_deprecated_string()})
    params = {'identifiers': user.email, 'action': action, 'email_students': True, 'reason': 'change    user    enrollment'}
    response = self.client.post(url, params)
    self.assertEqual(response.status_code, 200)
    return response
