Even if you just test your skill against your teacher, classmates, and training partners, you are still using some kind of "sport" format and apply "rules" that both persons will agree.
If you only test your skill within your own MA system, you may not test your skill enough against people from other MA systems. For example,
Without testing your skill against
- BJJ guys, you may never experience the "pull guard" and "jump guard"
- MT guys, you may never experience the "flying knee".
- ...
I think you misunderstand what you are testing. You are fixated on techniques.
Over the back of my house is the moors and the army training area. last night the Infantry recruits were out on exercise, getting ready for their final exercise where they are tested. You could hear the fire fights going on and see the shemoulies lighting up the area. Now, when it comes to that final exercise what do you think the instructors are going to be testing?
They
won't be testing the recruits weapon handling, their leadership skills, their drill, their field craft etc etc the instructors know they can do all of that, after all they taught them over the past few months but they don't know that when push comes to shove if the recruits can do it under pressure. They will be testing the man not the techniques..
This is what you do when you pressure test your techniques in the cage/ring/mat. You aren't testing your techniques (it doesn't matter what style either), if you have drilled them and drilled them they come as second nature, you know they work, what you are testing is YOU. Will you hold your nerve when there's a flurry of punches coming at you? will you get up if you are knocked down or curl up like a baby? Can you keep calm, assessing as you go along or are you going to lose your rage and flail in? The questions aren't about techniques, they work, it's about you, have you got 'it'.
Plenty of people haven't, ask any promoter. People phone on the morning of a fight with an 'injury, I've seen people take their medical then disappear never to be seen again, one lad even got as far as the cage door, turned around and went back to the changing room. It happens a lot.
Techniques work, you know they do, you've practised them on resisting people, you know all the various ways to put them on and if that doesn't do it you know how to transition to do another technique then another. You don't have to test them against anyone but you do have to test your nerve. Until you test yourself, until you know yourself and how you behave under pressure it won't matter how many different styles you train with because sure, you can use them in a 'sports' context but can you use them when you really need to or will you go to pieces?
It's not your MA skills that need testing, it's you.
After the first fight, fighters know whether they can compete or not so then it's still not about testing techniques it's about winning fights, doing what you know, using tactics to win against opponents.