如何模拟一个装饰函数 [英] How to mock a decorated function

问题描述

出于测试原因，我需要能够模拟在其他地方使用的装饰的内部/原始功能:

For testing reasons, I need to be able to mock the inner/original function of a decorated one which is used somewhere else:

在 mydecorator.py 中:

In mydecorator.py:

def my_decorator(f):
    def wrapped_f():
        print "decorated"
        f()
    return wrapped_f


@my_decorator
def function_to_be_mocked():
    print 'original'


def function_to_be_mocked_undecorated():
    print 'original'


def run_decorated():
    function_to_be_mocked()


def run_undecorated():
    decorated_funtion = my_decorator(function_to_be_mocked_undecorated)
    decorated_funtion()

如您所见，我有几个版本的原始函数 function_to_be_mocked，一个带有装饰器 my_decorator，另一个是裸".运行器函数 run_decorated() 调用 function_to_be_mocked 的修饰版本， run_undecorated() 调用未修饰版本并手动"应用修饰器.两者的结果是一样的:

As you can see, I have several versions of the original function function_to_be_mocked, one with the decorator my_decorator and one 'naked'. The runner function run_decorated() calls the decorated version of function_to_be_mocked and run_undecorated() calls the undecorated version and applies the decorator 'manually'. The result of both are the same:

decorated
original

现在我想测试 runner 函数，但我需要模拟原始函数 function_to_be_mocked 并且模拟的版本应该被装饰:

Now I want to test the runner function but I need to mock the original function function_to_be_mocked but also the mocked version should be decorated:

import unittest
import mydecorator
from mock import patch

def mock_function():
    print 'mockified'

class Test(unittest.TestCase):

    @patch('mydecorator.function_to_be_mocked_undecorated')
    def test_undecorated_mocked(self, mock_function_to_be_mocked_undecorated):
        mydecorator.function_to_be_mocked_undecorated = mock_function
        mydecorator.run_undecorated()
        assert 1==0

    @patch('mydecorator.function_to_be_mocked')
    def test_decoratorated_mocked(self, mock_function_to_be_mocked):
        mydecorator.function_to_be_mocked = mock_function
        mydecorator.run_decorated()
        assert 1==0

这对于未修饰的版本 test_undecorated_mocked 可以正常工作:

This works as expected for the undecorated version test_undecorated_mocked:

decorated
mockified

但装饰版给出:

mockified

所以装饰器消失了.

是否可以让装饰版本以与未装饰版本相同的方式工作，其中手动"应用装饰器?

Is it possible to get the decorated version working in the same way as the undecorated version, where the decorator is applied 'manually'?

我尝试在装饰器中暴露内部函数，但没有成功.

I tried to expose the inner function in the decorator without success.

我看到了这个问题 你如何模拟一个在单元测试中应用了装饰器的函数?但这对我没有帮助.

I saw this question How do you mock a function which has decorator apply to it in a unit test? but this doesn't help me.

推荐答案

Python在加载模块时应用装饰器，所以在test_decoratorated_mocked<中设置function_to_be_mocked为mock_function/code> 确实会将该函数更改为未修饰的函数.

Python applies the decorator when loading the module so setting function_to_be_mocked to mock_function in test_decoratorated_mocked would indeed change that function into an undecorated function.

如果要模拟 function_to_be_mocked，则需要再次手动添加装饰器:

You'd need to manually add the decorator again if you wish to mock function_to_be_mocked:

mydecorator.function_to_be_mocked = mydecorator.my_decorator(mock_function)

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