此脚本失败:
import mock class MyClass(object): @classmethod def my_method(cls): print('my_method') def mocked_method(cls): print('I want this method to get called') with mock.patch.object(MyClass,'my_method',mocked_method): MyClass.my_method()
例外:
Traceback (most recent call last): File "/home/foo/tmp/test_mocking_classmethod.py",line 14,in <module> MyClass.my_method() TypeError: unbound method mocked_method() must be called with MyClass instance as first argument (got nothing instead)@H_502_8@
解决方法
Python函数是
descriptors,Python将这些函数绑定到它们被查找的实例,或者在classmethod的情况下,绑定到类.因为你没有在替换函数上使用classmethod装饰器,所以它被错误地绑定(作为常规方法,因此没有传入cls).
只需手动将目标包装在classmethod装饰器中:
with mock.patch.object(MyClass,classmethod(mocked_method)): MyClass.my_method()
这里我手动应用了@classmethod装饰器,但您也可以直接在目标函数上使用它作为装饰器:
@classmethod def mocked_method(cls): print('I want this method to get called') with mock.patch.object(MyClass,mocked_method): MyClass.my_method()
演示:
>>> import mock >>> class MyClass(object): ... @classmethod ... def my_method(cls): ... print('my_method') ... >>> def mocked_method(cls): ... print('I want this method to get called') ... >>> with mock.patch.object(MyClass,classmethod(mocked_method)): ... MyClass.my_method() ... I want this method to get called@H_502_8@ @H_502_8@