Ahem... some folks do tend to write what first comes to mind.   Nevermind.   I think that it would be helpful if you’d elaborate a little bit on what approach you want to take.   In other words, “if I just now stumbled upon ‘the perfect test environment for my present purposes,’ how would I recognize it?   What, exactly, would it look like?   What, exactly, would it enable me to do that I cannot so easily do today?”

Also elaborate on just what this “application” looks like.   That word, after all, could mean absolutely anything.   When you say, “screens,” how are those constructed?   And so on.

Please put some serious thought into it.   The more thoroughly you are able to answer that hypothetical question, the more focused your search will be – and the more effectively we will be able to help you (and to learn from your experiences).

There are, as you have seen, almost a Roman legion of Test:: modules.   All of them are devised for particular purposes, to be useful in particular contexts (and hence, possibly useless in others).   You have, indeed, touched upon some of the most useful ones for certain general purposes ... but do they apply to yours?   Aye, there’s the rub, and only you can decide it.

That “less than diplomatic expression” accurately describes what will happen if you don’t.