def METHOD_NAME(self):
    """test for max length"""
    # get foreign key object id
    system_id = System.objects.get(system_name='system_1').system_id
    # get object
    form = SystemuserForm(
        data={
            'systemuser_name': 's' * 255,
            'system': system_id,
        }
    )
    # compare
    self.assertTrue(form.is_valid())