'Test deleting the grade using the publish mechanism'

def test_xmodule_runtime_publish_delete(self):

    module = self.set_module_grade_using_publish(self.grade_dict)
    module.system.publish(module, 'grade', self.delete_dict)
    student_module = StudentModule.objects.get(student=self.student_user, module_state_key=self.problem.location)
    self.assertIsNone(student_module.grade)
    self.assertIsNone(student_module.max_grade)
