返回扭曲的延迟后模拟无效

Question

我在扭曲试验单元测试中遇到模拟问题。被测函数 return 被推迟了，而我 return 从单元测试中推迟了。但是，一旦我 return 延迟，我应用的补丁似乎就被还原了，它不会等到延迟被解决。

请看下面的例子：

schedule.py

import time
from twisted.internet import task, reactor

class Schedule():
    def get_time(self):
        t = time.time()
        return task.deferLater(reactor, 2, lambda: t)

    def get_time_future(self):
        return task.deferLater(reactor, 2, lambda: time.time())

schedule_test.py

import mock
from twisted.trial import unittest
from schedule import Schedule

class ScheduleTest(unittest.TestCase):
    @mock.patch('schedule.time')
    def test_get_time(self, mock_time):
        mock_time.time.return_value = 1450407660
        d = Schedule().get_time()
        d.addCallback(self.assertEqual, 1450407660)
        return d

    @mock.patch('schedule.time')
    def test_get_time_future(self, mock_time):
        mock_time.time.return_value = 1450407660
        d = Schedule().get_time_future()
        d.addCallback(self.assertEqual, 1450407660)
        return d

并输出

test_schedule
ScheduleTest
    test_get_time ...                                                      [OK]
    test_get_time_future ...                                             [FAIL]

===============================================================================
[FAIL]
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/twisted/trial/_synctest.py", line 437, in assertEqual
    super(_Assertions, self).assertEqual(first, second, msg)
  File "/usr/lib/python2.7/unittest/case.py", line 515, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/usr/lib/python2.7/unittest/case.py", line 508, in _baseAssertEqual
    raise self.failureException(msg)
twisted.trial.unittest.FailTest: 1456370638.190432 != 1450407660

test_schedule.ScheduleTest.test_get_time_future
-------------------------------------------------------------------------------
Ran 2 tests in 4.024s

FAILED (failures=1, successes=1)

我在上面的例子中嘲笑 time 的方式有什么问题吗？

Answer 1

你嘲讽的方式确实有问题time。 mock 装饰器在进入测试函数时设置补丁，然后在退出时删除它们。但是，您返回的是 Deferred，这意味着 time.time 回调运行良好在测试函数退出后。

如果您只想继续使用类似模拟的修补界面，您可以使用 Twisted 的 TestCase.patch，我相信它会 Deferreds 考虑在内。

然而，mocking is a testing anti-pattern, and a much better way to deal with the passage of time is to use the documented API for testing the passage of time, twisted.internet.task.Clock.

Answer 2

因为 Glyph pointed out, using TestCase.patch 可以提供帮助。打补丁需要如下图：

def test_get_time_future(self):
    mock_time = MagicMock()
    mock_time.time.return_value = 1450407660
    self.patch(sys.modules['schedule'], 'time', mock_time)
    d = Schedule().get_time_future()
    d.addCallback(self.assertEqual, 1450407660)
    return d

此测试通过。

返回扭曲的延迟后模拟无效

Mock is not effective after twisted deferred is returned

python

unit-testing

twisted

mocking