I would probably write a test program and run it against the server. E.g.:
- Open Socket 1
- Send filter for pubkey on s1
- Open Socket 2
- Send kind0 event on s2
- Verify that it arrived on s1.
(Extend with other test cases, e.g. open another socket to ensure, event is sent with "historical" events before EOS.)
In this case, kind0s are not different from other relays though.