檢查函數是否在不改變其行爲的情況下被調用

Question

如何測試python函數被調用，而不改變它的行爲？

有很多相關的帖子，但我找不到他們中的一個，涵蓋了一切：

• How to test that a function is called within a function with nosetests變化（行爲）
• Patching a method without changing how the method works?（帶參數不起作用和返回值）

基本上，我只是需要監視函數來知道它是否被調用。

例如，下面的代碼片段具有非常令人驚訝的行爲

from unittest.mock import patch 

def func(a,b): 
    print('was called') 
    return a * b 

with patch('test.func') as patched_function: 
    print(func(4,5)) 

print(patched_function.called) 

輸出：

<MagicMock name='func()' id='1721737249456'> 
True 
was called 
20 
False 

雖然我只是期待

was called 
20 
True 

Answer 1

你應該爲函數創建一個裝飾像這樣：

class CheckCall(object): 
    called = False 

    def __init__(self, func): 
     self.func = func 

    def __call__(self *args, **kwargs): 
     self.called = True 
     return self.func(*args, **kwargs) 

那麼你可以申請你的裝飾，像這樣

with patch('test.func') as patched_function: 
    patched_function = CheckCall(patched_function) 
    print(patched_function.called) # Prints False 
    patched_function(...) 
    print(patched_function.called) # Prints True