def METHOD_NAME(self):
    djangocms_blog.admin.register_extension(PostPlaceholderExtension)
    with self.assertRaises(Exception):  # noqa: B017
        djangocms_blog.admin.register_extension(PostPlaceholderExtension)
    djangocms_blog.admin.unregister_extension(PostPlaceholderExtension)
    with self.assertRaises(Exception):  # noqa: B017
        djangocms_blog.admin.unregister_extension(PostPlaceholderExtension)