Question

def testedFunction(param):
    try:
        dic = OrderedDict(...)
    except Exception:
        ...

我想单元测试异常，抛出给定函数，所以为了实现这一点，我尝试使用unittest.mock.patch或unittest.mock.patch.object，两者都失败了：

TypeError: can't set attributes of built-in/extension type 'collections.OrderedDict'

我已经阅读了一些主题并搜索了像forbiddenfruit这样的工具，但这似乎根本不起作用。

我如何模拟那种类的构造函数？

Answer 1

这对我有用。当对象构造尝试调用mock时，它会使用mock修补类OrderedDict并抛出异常：

import collections
from unittest.mock import patch

def testedFunction(param):
    try:
        dic = collections.OrderedDict()
    except Exception:
        print("Exception!!!")


with patch('collections.OrderedDict') as mock:
    mock.side_effect = Exception()
    testedFunction(1)

跑步时显示：

python mock_builtin.py
Exception!!!

Process finished with exit code 0

对于'from collections import OrderedDict'语法，需要模拟导入的类。因此，对于名为mock_builtin.py的模块，下面的代码给出了相同的结果：

from collections import OrderedDict
from unittest.mock import patch

def testedFunction(param):
    try:
        dic = OrderedDict()
    except Exception:
        print("Exception!!!")


with patch('mock_builtin.OrderedDict') as mock:
    mock.side_effect = Exception()
    testedFunction(1)

Python，单元测试，模拟内置/扩展类型类方法

1 个答案: