您可以将patch（）方法用于 side_effect .
每当调用mock时要调用的函数。请参见“副作用”属性。用于引发异常或动态更改返回值。
例如 main.py :

import os

def func1():
    print('func1')

def func2():
    print('func2')

def main():
    path_one = 'path_one'
    path_two = 'path_two'

    if os.path.exists(path_one):
        func1()

    elif os.path.exists(path_two):
        func2()
``` `test_main.py` :

from main import main
from unittest import TestCase, mock
import unittest

class TestMain(TestCase):
@mock.patch('main.os.path.exists')
def test_main(self, mock_exists):
def side_effect(path):
if(path == 'path_one'):
return False
if(path == 'path_two'):
return True

    mock_exists.side_effect = side_effect
    main()

if name == 'main':
unittest.main()

测试结果：

func2
.

Ran 1 test in 0.001s

OK