not_change.py

# -*- coding:utf-8 -*-
import mock
from not_change_work import work

with mock.patch("not_change_source.add") as m:
    result = work(1, 2)
    print(result)
    print(m.called)

# [1, 2]
# False

with mock.patch("not_change_work.add") as m:
    result = work(1, 2)
    print(result)
    print(m.called)

# [1, 2]
# False

not_change_source.py

# -*- coding:utf-8 -*-
def add(x, y):
    return [x, y]

not_change_work.py

# -*- coding:utf-8 -*-
from not_change_source import add


def work(x, y, add=add):
    return add(x, y)