在Python中，如何模拟c扩展类? [英] In Python, how to mock a c extension class?

问题描述

我正在尝试模拟一个在其中使用c扩展类的类函数，但我得到了TypeError: can't set attributes of built-in/extension type 'y.cExtensionClass'. code.py是一个遗留代码，我真的不希望对其进行更改.有什么建议吗?

I'm trying to mock a class function which uses a c extension class inside it as follows, but I get TypeError: can't set attributes of built-in/extension type 'y.cExtensionClass'. code.py is a legacy code, and I really rather not to change it. Any suggestion?

code.py:

from x.y import cExtensionClass

class CodeClass():

    @staticmethod
    def code_function():
         cExtensionClass().cExtensionFunc()

test.py:

import code
from x.y import cExtensionClass

class test(unittest.TestCase):

    def test_code_function(self)
        with patch.object(cExtensionClass, 'cExtensionFunc') as cExtensionFuncMock:   
            cExtensionFuncMock.return_value = None
            code.CodeClass.code_function()
            cExtensionFuncMock.assert_called_with()

谢谢

推荐答案

修补code.cExtensionClass(不是x.y.cExtensionClass). 用import code代替from code cExtensionClass.

Patch code.cExtensionClass (not x.y.cExtensionClass). Do import code instead of from code cExtensionClass.

import unittest

from mock import patch, Mock

import code

class test(unittest.TestCase):
    def test_code_function(self):
        with patch('code.cExtensionClass') as m:
            m.return_value.cExtensionFunc = func = Mock()
            code.CodeClass.code_function()
            func.assert_called_with()

    #@patch('code.cExtensionClass')
    #def test_code_function(self, m):
    #    m.return_value.cExtensionFunc = func = Mock()
    #    code.CodeClass.code_function()
    #    func.assert_called_with()

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