检查函数是否在不改变其行为的情况下被调用

Question

如何测试python函数被调用，而不改变它的行为？

有很多相关的帖子，但我找不到他们中的一个，涵盖了一切：

• How to test that a function is called within a function with nosetests变化（行为）
• Patching a method without changing how the method works?（带参数不起作用和返回值）

基本上，我只是需要监视函数来知道它是否被调用。

例如，下面的代码片段具有非常令人惊讶的行为

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) 

输出：

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

虽然我只是期待

was called 
20 
True 

Answer 1

你应该为函数创建一个装饰像这样：

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) 

那么你可以申请你的装饰，像这样

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