Multiple OS on single server for code testing

I'm stuck and looking for some possible solutions. We have a bash script (I can't change the language it have to be bash that do a lot of changes to base OS ( Linux Redhat, 5,6.7 and suse 11 and 12) and the script is growing a lot, mistakes are made and so on, because there is no unified testing.

I'm looking to build some testing environment where I could send the script and it would spun images of the OS, each version..., copy over the script, and run test on it with bats testing framework and than send the reports to one place for me to see...

One solution I thought of as default is to use ESXi server, create VM for each OS, make a snapshot .. and that somehow automate the testing and reverting back to default snapshot...

I was thinking about docker as well, but not sure if that would work, since the script is setting services/ starting and stopping stuff.. it more likely need full working OS

Any ideas, or am I not googling hard enough ? :D