def test_failIfIdenticalNegative(self):
        """
        C{failIfIdentical} raises C{failureException} if its first and second
        arguments are the same object.
        """
        x = object()
        self.failUnlessRaises(self.failureException,
                              self.failIfIdentical, x, x)

        C{failIfIdentical} raises C{failureException} if its first and second
        arguments are the same object.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_assertions.py