Python，單元測試，模擬內置/擴展類的類方法

Question

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

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

我想單元測試異常，拋出給定的函數，所以爲了實現這一點，我試過使用unittest.mock.patch或unittest.mock.patch.object，無論失敗：

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

我看了一些話題已經搜查像forbiddenfruit工具，但似乎都沒有給不工作。

我該如何模擬這種類的構造函數？

Answer 1

這對我有效。它修補類OrderedDict用模擬物，並拋出異常，當對象的構造試圖調用模擬：

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) 

時運行它顯示：

python mock_builtin.py 
Exception!!! 

Process finished with exit code 0 

對於「從收藏導入OrderedDict」語法，進口類必須嘲笑。因此，對於名爲mock_builtin.py的模塊，以下代碼給出了相同的結果：

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)