Python:使用@patch在方法内模拟类的实例

# MyClass.py
from DependencyClass import DependencyClass

class MyClass:
    def __init__(self):
        self.dependency = DependencyClass()

    def my_method(self):
        return self.dependency.do_something()

# test_MyClass.py
import unittest
from unittest.mock import patch, MagicMock
from MyClass import MyClass

class TestMyClass(unittest.TestCase):
    @patch('__main__.DependencyClass')
    def test_my_method(self, MockDependencyClass):
        # 创建一个模拟的 DependencyClass 实例
        mock_instance = MockDependencyClass.return_value
        # 设置模拟方法的返回值
        mock_instance.do_something.return_value = 'mocked result'

        my_class = MyClass()
        result = my_class.my_method()

        # 断言方法被调用，并且返回了预期的值
        mock_instance.do_something.assert_called_once()
        self.assertEqual(result, 'mocked result')

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