Question

I have the following construct, in which I derive a class from unittest.TestCase, in which a method is called that is defined in the actual test class MyTests.

import unittest

class TestCase1(unittest.TestCase):

    @classmethod
    def setUpClass(cls):  
        print cls.extra()

class TestCase2(TestCase1):

    @classmethod
    def setUpClass(cls):
        TestCase1.setUpClass()

class MyTests(TestCase1):

    @classmethod
    def extra(cls):
        return 42

    def test1(self):
        pass

if __name__ == '__main__':
    unittest.main()

The above code, as it stands, works as expected. When I execute the tests, the setUpClass of TestCase1 is run, which executed extra() defined in MyTests.

The problem comes into play when I want to use TestCase2 instead TestCase1, i.e. when I change the ‘1’ to ‘2’ in the following line:

class MyTests(TestCase2): # using TestCase2 instead

The idea is that setUpClass of TestCase2 is called, which in itself calls setUpClass from the basic class, i.e. TestCase1, which executes the method extra. However, I get an attribute error:

AttributeError: type object 'TestCase1' has no attribute 'extra'

I seem to misunderstand some concepts here. I would have expected my code to work in both cases (maybe there is some error), or to fail in both cases. Any ideas what here might be wrong or how I can fix the problem are greatly appreciated.

Answer 1

I highly recommend using super instead of TestCase1.setUpClass().