mock.patch 方法旨在临时模拟给定的对象.如果你想永久改变一个函数的返回值，你可以简单地通过指定一个 Mock 对象并指定 return_value 给它来覆盖它:

The mock.patch method is meant to temporarily mock a given object. If you want to permanently alter the return value of a function, you can simply override it by assigning to it with a Mock object with return_value specified:

import foo
from unittest.mock import Mock
foo.get_shard = Mock(return_value=11)