Python unittest - setUpClass() 给我带来了麻烦 - 为什么我不能像这样继承？
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Python unittest - setUpClass() is giving me trouble - why can't I inherit like this?
提问by jononomo
I have unittest code like the following:
我有如下的单元测试代码：
import unittest
class MyUnitTest(unittest.TestCase):
def setUpClass(self):
do_something_expensive_for_all_sets_of_tests()
class MyFirstSetOfTests(MyUnitTest):
def setUpClass(self):
super(MyFirstSetOfTests, self).setUpClass()
do_something_expensive_for_just_these_first_tests()
def test_one(self):
...
def test_two(self):
...
class MySecondSetOfTests(MyUnitTest):
def setUpClass(self):
super(MySecondSetOfTests, self).setUpClass()
do_something_expensive_for_just_these_second_tests()
def test_one(self):
...
def test_two(self):
...
if __name__ == '__main__':
unittest.main()
When I try to run this code, I get an error like this:
当我尝试运行此代码时，出现如下错误：
======================================================================
ERROR: setUpClass (__main__.MyFirstSetOfTests)
----------------------------------------------------------------------
TypeError: unbound method setUpClass() must be called with MyFirstSetOfTests instance as first argument (got nothing instead)
----------------------------------------------------------------------
采纳答案by Martijn Pieters
setUpClassmustbe a class method. From the documentation:
setUpClass必须是类方法。从文档：
A class method called before tests in an individual class run.
setUpClassis called with the class as the only argument and must be decorated as aclassmethod():@classmethod def setUpClass(cls): ...See Class and Module Fixturesfor more details.
在单个类中运行测试之前调用的类方法。
setUpClass使用类作为唯一参数调用，并且必须装饰为classmethod()：@classmethod def setUpClass(cls): ...有关更多详细信息，请参阅类和模块装置。
Your version is missing the @classmethoddecorator:
您的版本缺少@classmethod装饰器：
class MyUnitTest(unittest.TestCase):
@classmethod
def setUpClass(cls):
do_something_expensive_for_all_sets_of_tests()
class MyFirstSetOfTests(MyUnitTest):
@classmethod
def setUpClass(cls):
super(MyFirstSetOfTests, cls).setUpClass()
do_something_expensive_for_just_these_first_tests()
The error is thrown because MyFirstSetOfTests.setUpClass()is called on the class, not on an instance, but you didn't mark your method as a classmethodand thus it was not passed in the automatic selfargument. In the above updated code I used clsinstead, to reflect that the name references the class object.
抛出错误是因为MyFirstSetOfTests.setUpClass()在class上调用，而不是在实例上调用，但是您没有将方法标记为 a classmethod，因此它没有在自动self参数中传递。在上面我使用的更新代码中cls，以反映名称引用了类对象。
