Python mock:模拟继承的基类

2022-01-08 00:00:00 python inheritance mocking unit-testing

问题描述

我正在测试一个从另一个非常复杂的类继承的类，具有数据库连接方法和一堆依赖项.我想模拟它的基类，以便我可以很好地使用子类中定义的方法，但是在我从模拟类继承的那一刻，对象本身变成了模拟并丢失了它的所有方法.

I am testing a class that inherits from another one very complex, with DB connection methods and a mess of dependences. I would like to mock its base class so that I can nicely play with the method defined in the subclass, but in the moment I inherit from a mocked class, the object itself turns a mock and loses all its methods.

如何模拟超类?

这种情况或多或少可以概括为:

More or less the situation can be summed up in this:

import mock

ClassMock = mock.MagicMock()

class RealClass(ClassMock):

    def lol(self):
        print 'lol'

real = RealClass()
real.lol()  # Does not print lol, but returns another mock

print real # prints <MagicMock id='...'>

这是一个简化的案例.实际发生的是 RealClass 扩展了 AnotherClass，但我设法拦截了 AnotherClass 并将其替换为模拟.

This is a simplified case. What is actually happening is that RealClass extends AnotherClass, but I managed to intercept the AnotherClass and replace it with a mock.

解决方案

这应该适合你.

import mock

ClassMock = mock.MagicMock # <-- Note the removed brackets '()'

class RealClass(ClassMock):

    def lol(self):
        print 'lol'

real = RealClass()
real.lol()  # Does not print lol, but returns another mock

print real # prints <MagicMock id='...'>

您不应该像以前那样传递类的实例.mock.MagicMock 是一个类，所以你直接传递它.

You should'nt pass an instance of the class as you did. mock.MagicMock is a class, so you pass it directly.

In [2]: inspect.isclass(mock.MagicMock)
Out[2]: True

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