I use git and commit configs/setup/scripts/etc. to it. I at least have a road map for how to get everything back this way. Testing this can be difficult, but it really depends on what you care about really.

• Testing my kopia backups of important data? that I manually test every once n' while.
• Testing if my ZFS setup script is 100% identical to my setup? that's not that important, as long as I have a general idea I can figure out the gaps and improve the script for the next time around. Obviously, you can spend a lot more time ensuring scripts and what not stays consistent, but it depends on what you care about!

For a lot of my service config, git has always worked well for me and I can go back to older configs if needed. You can get super specific here and save versions in git, then have something update the versions (e.g. WUD)