It will just be a manual test that only happens when you choose a relay to test and press the test button.   I'm not even sure I should bother persisting the results beyond a restart, or even preventing double-click from testing twice.

So yes you could imagine better more automatic things, but this should save people 98% of the time they currently have to spend researching which relays are appropriate for which purposes.  Test... ah there is one.  Switch!  Next relay, test... nope... next relay...  You could work things out in under a minute now.