saltstack testing: render as each host in turn

We test saltstack scripts on vagrant boxes. It sometimes happens that while testing changes for host A, we inadvertently cause a problem for host B.

I'd like to write a script that will at least render (call show_sls) as if the minion id were each host in turn. This will remove at least one class of error.

I can think of some hacky ways of doing this, like changing the contents of /etc/salt/minion_id on each iteration. But are there better ways?

I know far too little about how to test salt scripts well. All suggestions most welcome.