模拟类属性

Question

我有一个要模拟的具有单个类属性的类

my_class.py

class MyClass:

    __attribute = ['123', '456']

test_my_class.py

import pytest
from directory.my_class import MyClass

def test_1(mocker):
    with mocker.patch.object(MyClass, '__attribute', {'something': 'new'}):
        test = MyClass()

我明白了：

E           AttributeError: <class 'directory.my_class.MyClass'> does not have the attribute '__attribute'

我在尝试时也遇到了同样的错误：

def test_2(mocker):
    with mocker.patch('directory.my_class.MyClass.__attribute', new_callable=mocker.PropertyMock) as a:
        a.return_value = {'something': 'new'}
        test = MyClass()

我还尝试了直接分配以及这篇文章中的其他建议： Better way to mock class attribute in python unit test

我的项目正在使用来自此插件的模拟装置：https://pypi.org/project/pytest-mock/

Answer 1

您可以使用PropertyMock 完成上述操作

from unittest.mock import patch, PropertyMock

class MyClass:
  attr = [1, 2, 3]

with patch.object(MyClass, "attr", new_callable=PropertyMock) as attr_mock:
  attr_mock.return_value = [4, 5, 6]

  print(MyClass.attr) # prints [4, 5, 6]

print(MyClass.attr) # prints [1, 2, 3]

文档参考：https://docs.python.org/3/library/unittest.mock.html#unittest.mock.PropertyMock