Agree. As far as I remember I think I did it that way because I couldn't put `redis` in `URI_PASSTHROUGH` (it would break a classic redis connection at https://github.com/blaze33/kombu/blob/f30f669adcc7ed3a0e64d72ed88b6cf90dfcba50/kombu/connection.py#L179).
Also, `transport_cls` is `redis` in both url and socket case so it cannot be used to test how to print `as_uri`.