为什么我不能用unittest.mock.patch？

Question

我正在尝试为函数编写UT，同时模拟其他函数。两者位于同一模块中。似乎unittest.mock.补丁（）调用传递没有错误，但没有模拟任何东西，因此示例代码中出现异常。所以，我的问题是：如何用unittest.mock.补丁？你知道吗

import unittest
import unittest.mock

def foo():
        raise Exception("not implemented")

def bar():
        foo()

class UT(unittest.TestCase):

        def testBar(self):
                with unittest.mock.patch('mock_test.foo',spec=True) as mock_foo:
                        bar()    # <- original foo is called here

unittest.main()

Answer 1

下面是一种使用unittest.mock.patch并修补foo返回的方法。参见示例中的注释：

import unittest
from unittest.mock import patch


def foo():
        raise Exception("Not implemented")


def bar():
        return foo()


class UT(unittest.TestCase):

        def testBar(self):
            # foo is mocked to raise a ValueError and catch it during the test
            with patch('__main__.foo', side_effect=ValueError):
                with self.assertRaises(ValueError):
                    bar()

            # foo is mocked to raise and exception and catch it during the test
            with patch('__main__.foo', side_effect=Exception):
                with self.assertRaises(Exception):
                    bar()

            # foo is mocked to return 1
            with patch('__main__.foo', return_value=1):
                self.assertEqual(bar(), 1, "Should be equal to 1")

            # foo is mocked to return an object
            with patch('__main__.foo', return_value={}):
                self.assertIsInstance(bar(), dict, "Should be an instance of dict")


unittest.main()

输出：

.
                                   
Ran 1 test in 0.001s

OK

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