我在SO上四处张望,但没有找到我想要的东西,我很确定这已经在其他地方得到了解答。所以我在函数中有两个文件写入,如下所示:
def write_files():
with open("a.txt", 'w') as f_h:
f_h.write("data1")
with open("b.txt", 'w') as f_h:
f_h.write("data2")
我如何选择性地模拟f_h.write(),以便一个返回异常,而另一个不返回?我尝试设置side_effect,但不清楚适合的位置。我尝试过的测试代码具有以下内容:
from unittest.mock import patch, call, mock_open
import unittest
class Tester(unittest.TestCase):
def test_analyze(self):
with patch("builtins.open", mock_open(read_data="data")) as mf:
# mf.side_effect = [None, Exception()] ?
write_files()
if __name__ == '__main__':
unittest.main()
两件事:您必须模拟上下文管理器,例如__enter__
的结果,并且您必须将副作用放在模拟文件句柄的write
方法上(例如__enter__
调用的结果):
class Tester(unittest.TestCase):
def test_analyze(self):
with patch("builtins.open", mock_open(read_data="data")) as mf:
fh_mock = mf.return_value.__enter__.return_value
fh_mock.write.side_effect = [None, Exception]
with self.assertRaises(Exception):
write_files()