Question

我试图创建一个单元测试来检查Python 3.4代码的错误处理。我在模拟中使用MagicMock替换子函数并将异常作为side_effect引发，然后使用unittest中的assertRaises来检查引发的异常。

不幸的是，尽管代码似乎正在处理异常，但由于异常，测试似乎正在崩溃。我尝试重写测试以使用try / except循环无效，我尝试将其转换为nose2 @raise AttributeError无效。

代码中的错误处理是否以某种方式阻止测试捕获引发的异常？

代码：

import unittest2 as unittest
from mock import MagicMock

class Service():

    def _execute(self, entity, destport):

        print("setting format to json")
        self.format = "json"

        try:
            print("call _reply_in_json")
            getattr(self, "_reply_in_%s" % self.format)(entity, destport)
            return ""
        except AttributeError:
            print("Invalid format requested")
            err = "invalid format requested"
            return err


class TestService(unittest.TestCase):

    def test_executeAttributeError(self):
        self.entity = "butter"
        self.destport = 54
        self.ret = False

        print("## Starting test_executeAttributeError for CsvDs")

        # Set up test objects
        testDS = Service()
        testDS._reply_in_json = MagicMock(name='_reply_in_json', side_effect=Exception(AttributeError))

        # Run the test
        with self.assertRaises(AttributeError):
            print("Execute new request")
            self.ret = testDS._execute(self.entity, self.destport)

        if self.ret:
            self.assertEqual(self.ret, "invalid format requested")

            # Check the call was made correctly.
            testDS._reply_in_json.assert_called_once_with(self.entity, self.destport)
        else:
            print("nothing returned")

        print("test_executeAttributeError for CsvDs completed successfully\n")

if __name__ == '__main__':
   suite = unittest.TestLoader().loadTestsFromTestCase(TestService)
   unittest.TextTestRunner(verbosity=2).run(suite)

输出：

## Starting test_executeAttributeError for CsvDs
Execute new request
setting format to json
call _reply_in_json

Error
Traceback (most recent call last):
  File "daltest/test_test.py", line 37, in test_executeAttributeError
     self.ret = testDS._execute(self.entity, self.destport)
  File "daltest/test_test.py", line 13, in _execute
    getattr(self, "_reply_in_%s" % self.format)(entity, destport)
  File "/usr/lib/python3.4/site-packages/mock/mock.py", line 1062, in __call__
    return _mock_self._mock_call(*args, **kwargs)
  File "/usr/lib/python3.4/site-packages/mock/mock.py", line 1118, in _mock_call
    raise effect
Exception: <class 'AttributeError'>


Process finished with exit code 0

Answer 1

你没有在副作用中引发一个AttributeError，你提出了一个以AttributeError为参数的基本异常。直接使用实际的例外：

testDS._reply_in_json = MagicMock(name='_reply_in_json', side_effect=AttributeError)

另请注意，assertRaises将失败，因为_execute会捕获该异常并返回错误消息，因此测试用例本身不会看到任何异常。

python assertRaise没有捕获MagicMock异常

1 个答案: