Question

我想将基于Python的unittest模块的python测试工具从Python2升级到Python3。但是，unittest.expectedFailure装饰器似乎不再具有相同的效果。尤其是，即使规范实际上是相同的，以下代码也会根据Python版本而具有不同的行为：

#!/usr/bin/env python2
#!/usr/bin/env python3
# Switch between the two lines above to get the different outcome

import unittest

class ComparisonTests(unittest.TestCase):

    def runTest(self):
        """ This method is needed even if empty """

    def add_test(self, the_suite):
        def testMain():
            self.testFunc()
        testMain = unittest.expectedFailure(testMain)
        the_case = unittest.FunctionTestCase(testMain)
        the_suite.addTest(the_case)

    def testFunc(self):
        self.assertTrue(False)

if __name__ == '__main__':
    SUITE = unittest.TestSuite()
    ComparisonTests().add_test(SUITE)

    the_runner = unittest.TextTestRunner(verbosity=2)
    the_runner.run(SUITE)

如果我保留第一行（#!/usr/bin/env python2）并在MacOS 10.14.1和Python 2.7.15上运行，则输出如下：

unittest.case.FunctionTestCase (testMain) ... expected failure

----------------------------------------------------------------------
Ran 1 test in 0.000s

OK (expected failures=1)

这是我期望的行为。但是，如果我切换到将使用Python #!/usr/bin/env python3的第二行（3.7.3），则会得到以下信息：

unittest.case.FunctionTestCase (testMain) ... FAIL

======================================================================
FAIL: unittest.case.FunctionTestCase (testMain)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "./unittest_test_2.py", line 12, in testMain
    self.testFunc()
  File "./unittest_test_2.py", line 18, in testFunc
    self.assertTrue(False)
AssertionError: False is not true

----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (failures=1)

看起来unittest.expectedFailure装饰器已被忽略。查看源代码，我可以看到明显的区别：

# Python 3.7 source:
def expectedFailure(test_item):
    test_item.__unittest_expecting_failure__ = True
    return test_item

# Python 2.7 source:
def expectedFailure(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        try:
            func(*args, **kwargs)
        except Exception:
            raise _ExpectedFailure(sys.exc_info())
        raise _UnexpectedSuccess
    return wrapper

如何在unittest的Python3版本中定义预期的失败？

Answer 1

unittest.expectedFailure装饰器的Python 3版本预期将在单元测试用例上运行，而不是像在Python 2中那样在方法上运行。因此，为了使上述测试工具能够与Python 3一起使用，需要在expectedFalure上使用the_case装饰器，如下所示：

the_case = unittest.FunctionTestCase(testMain)
the_case = unittest.expectedFailure(the_case)

Python3中忽略的Python单元测试预期失败

1 个答案: