python模拟断言不会被调用一次

Question

模拟数据库查询：我正在尝试模拟数据库查询并断言调用了save，但是断言失败。有人可以帮忙吗？

models.py

import peewee

class A():
    human = CharField()
    Age  = CharField()

app.py

def get_A():
  return models.select().where(models.A.Age="5")

def update_A():
  age = get_A()
  for i in age:
     i.Age = 10
     i.save()

test.py

def build_mock_A():
  a = A()
  a.human = "hath"
  a.Age.  = 5
  return a

@patch('app.get_A')
def test_A(self,mock_get_A):
   mock_get_A.return_value = build_mock_A()
   app.update_A()
   mock_get_A.save.assert_called_once()

错误：

 raise AssertionError(msg)
 AssertionError: Expected 'save' to have been called once. Called 0 times.