def get_edit_url(self, project_slug, step_order):
        return reverse(self.url_name, args=(project_slug, step_order))
self.url points to using the view for creating a new step. Use this
dataset/ETHPy150Open python/raspberryio/raspberryio/project/tests/test_views.py/ProjectStepCreateEditTestCase.get_edit_url