Hellooo codeforces comunity!

I have a rather technical question about gym/mashup problems: is it possible to have "pretests" and "system tests". It is know that is possible for official ("rated") rounds, not only that it is possible, it happens every time at the end of the round. There is also a "hacking", but i wouldn't expect that to be possible for just some mashup...

I have made a lot problems on Polygon and made them into a gym contests by now (around 10-15 contests), but every time i made "system tests" before contest and they were the one that solutions were tested on during the contest. But now, I'm looking into possible new formats like Facebook Hackercup that have a limited "pretests", and just have solutions be tested on the real test after the contest.

I know about a rather time consuming proces so that this can be done, and it would be this: just have pretests as your only test on Polygon as long as contest is running on Codeforces. After contest, make new tests on Polygon, make package and just push them to Codeforces. Now you can rejudge all of the submitions on this new tests from Codeforces, but the pretests are lost basically.

However, "Create tests" page on Polygon has "Create testset" and really, you can create other testsets. And this works fine on Polygon... So lets test it: when I tried it out on Codeforces, it only tested solutions on testset "Tests" (the default one), not on the others. So this could be a "pretests" part of the question. But there is no easy way of making other testsets default on Polygon, or going on next testset in Codeforces, so no easy way to switch from "pretests" to "system tests".

At first i though that going to "Adm." tab on contest page (on Codeforces) and then just doing something with "Rejudge on next testset" could do what i want, but after submitting a few solutions i still see "To rejudge submissions: 0" what I interpret as Codeforces not knowing there are more testsets for problem? Maybe I'm just wrong and there is way to do it...

So finally, my question is: is there an easy way to make "pretests" and "system test" for gym contests using builtin methods on Polygon and Codeforces? IMO testsets on Polygon look like a way to go, but I suspect Codeforces is not reading them correctly or I'm just looking at the wrong place...

Thank you in advance, any help is appreciated!