Python中实例变量的模拟方法 [英] Mocking Methods on an Instance Variable in Python

问题描述

我正在尝试找出如何正确模拟一个实例变量，该实例变量是具有父类使用的方法的另一个类的实例.

I'm trying to figure out how to properly Mock an instance variable which is an instance of another class that has methods used by the parent class.

这是问题域的简化示例:

Here's a simplified example of the problem domain:

import unittest
import mock

class Client:
    def action(self):
        return True

class Service:
    def __init__(self):
        self.client = Client()

class Handler:
    def __init__(self):
        self._service = Service()

    def example(self):
        return self._service.client.action()


class TestHandler(unittest.TestCase):

    @mock.patch('__main__.Handler._service')
    def test_example_client_action_false(self):
        """Test Example When Action is False"""
        handler = Handler()
        self.assertFalse(handler.example())


if __name__ == '__main__':
    unittest.main()

结果测试引发:

AttributeError: __main__.Handler does not have the attribute '_service'

如何正确模拟Service或Client，以使action为测试用例返回False?

How do I properly mock the Service or Client such that action returns False for my test case?

推荐答案

可以通过模拟操作返回值来完成

Can be done by mock the action return value

class TestHandler(unittest.TestCase):

@mock.patch('__main__.Client.action')
def test_example_client_action_false(self, mock_client_action):
    """Test Example When Action is False"""
    mock_client_action.return_value = False
    handler = Handler()
    self.assertFalse(handler.example())

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