如何在 Python 中对依赖项进行猴子补丁？

Question

模拟一个依赖的方法对我不起作用。当我需要测试的方法调用它的依赖方法时，调用的是真正的方法，而不是它的mock版本。

我确实有以下文件：

myLibrary.py

from src.myOtherLibrary import myOtherLibrary
class myLibrary():
    def __init__():
        self.myVar = myOtherLibrary() #dependancy

    def my_method():
        method1 = self.method1()

        externalMethod2 self.myVar.method2() #method2 called from the external class myOtherLibrary

        return method1 + externalMethod2

    def method1():
        return "method1 from myLibrary..."

src/myOtherLibrary.py

class myOtherLibrary():
    def method2():
        return "method2 from myOtherLibrary..."

最后是单元测试：

TestMyLibrary.py

import unittest
import mock
from myLibrary import myLibrary
from src.myOtherLibrary import myOtherLibrary
class TestMyLibrary(unittest.TestCase):
    @mock.patch('myLibrary.myLibrary.method1') #mocking this works because it's a sibling method from my_method() to test
    @mock.patch('src.myOtherLibrary.myOtherLibrary.method2') #this does not work because it's an external class from myLibrary
    def test_my_method(my_method1_to_mock, my_method2_to_mock):
        my_method1_to_mock.return_value = "something_to_return.."
        my_method2_to_mock.return_value = "something_else_to_return.."

        myLibraryVar = myLibrary()
        result = myLibraryVar.my_method()
        print result #I would expect to see this: "something_to_return..something_else_to_return.."
                     #But it actually prints this: "something_to_return..method2 from myOtherLibrary..."
                     #So mocking is not working for method2

        self.assertEqual('something_to_return..something_else_to_return..', result)

if __name__ == '__main__':
    unittest.main()

也许值得一提的是 myLibrary.py 和 TestMyLibrary.py 位于同一个文件夹中，但 myOtherLibrary.py 位于不同的文件夹级别。

我希望你能帮我找到我在这里缺少的东西。

任何建议都将不胜感激。 谢谢。

Answer 1

你不能patch 那样，因为你试图模拟的方法是类方法而不是函数。所以你需要使用patch.object。

@mock.patch.object(myLibrary, 'method1') 
@mock.patch.object(myOtherLibrary, 'method2') 
...