Server did not fail.

Raise code

        cls.check_allowed_hosts(['testserver'])
        try:
            super().setUpClass()
        except RuntimeError:
            # LiveServerTestCase's change to ALLOWED_HOSTS should be reverted.
            cls.check_allowed_hosts(['testserver'])
        else:
            raise RuntimeError('Server did not fail.')
        cls.set_up_called = True

    @classmethod
    def tearDownClass(cls):
        # Make tearDownClass() a no-op because setUpClass() was already cleaned
        # up, and because the error inside setUpClass() was handled, which will
        # cause tearDownClass() to be called when it normally wouldn't.