BobMc What exactly you mean by test folder? An exact copy of your whole archive? You can just make backup/copy of your current archive and call your existing archive a test copy. And restore back if something goes wrong.
Anyway it is strongly recommended to setup regular backups of your archive before you starting doing anything. Not just one time backup or one time test copy, a regular backups with versioning. Mistakes happen, organizing your archive is time consuming, you don’t want to do that over again. You don’t need to buy expensive backup solutions, just use what is available: https://tonfotos.com/articles/all-you-need-to-know-about-backups-on-windows/