为什么嘲笑在调用时忽略了传递给嘲笑方法的实例/对象? [英] Why does mock ignore the instance/object passed to a mocked out method when it is called?

问题描述

我最近注意到，如果我使用mock.patch模拟方法，则不会在call_args字段中列出传递给模拟方法的实例对象.这是设计使然吗?下面的代码/输出可能会更好地解释我的意思:

I have recently noticed that if I mock out a method using mock.patch it doesn't list the instance object passed to the mocked method in the call_args field. Is this by design? Code/output below may better explain what I mean:

#!/usr/bin/env python2

from mock import patch

class Dog(object):
    def bark(self):
        print("Woof woof!")

Dog().bark()

def new_method(*args):
    print("args = %s" % str(args))

Dog.bark = new_method

Dog().bark()

with patch.object(Dog, "bark"):
    d = Dog()
    d.bark()
    print("d.bark was called: %s" % str(d.bark.called))
    print("d.bark was called with args/kwargs: %s" % str(d.bark.call_args))

输出为:

Woof woof!
args = (<__main__.Dog object at 0x7f42c2dbc3d0>,)

# Mocking bit
d.bark was called: True
d.bark was called with args/kwargs: ((), {})

您可以看到，当实例对象替换bark时，该实例对象已传递给new_method.但是您无法在模拟方法的call_args中看到它.这不是很奇怪吗?我正在使用python模拟库的1.01版.

You can see that the instance object is passed to new_method when it replaces bark. But you cannot see it in the call_args of the mocked out method. Isn't this strange? I am using version 1.01 of the python mock library.

推荐答案

通过

with patch.object(Dog, "bark"):

要修补Dog.bark方法的静态实例，是因为要修补Dog类而不是Dog对象.

You are patching the static instance of Dog.bark method because you are patching Dog class and not a Dog object.

现在，模拟方法将被称为静态方法，而不是对象方法:这意味着self属性将不会通过.

Now the mock method will be called as a static method and not as object method: that means the self attribute will not passed.

如果要创建具有与原始方法相同签名的补丁，则可以使用autospec=True属性:在这种情况下，模拟方法将是对象方法，而不是静态方法.

If you want create a patch with the same signature of original method you can use autospec=True attribute: in this case the mock method will be an object method instead of a static method.

>>> from mock import patch
>>> with patch.object(Dog, "bark", autospec=True):
...     d = Dog()
...     d.bark()
...     print("d.bark was called with args/kwargs: %s" % str(d.bark.call_args))
... 
<MagicMock name='bark()' id='139848306278672'>
d.bark was called with args/kwargs: call(<Dog object at 0x7f30f89ef390>)

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