I am tasked with updating plugins and core on a number of blogs that I am completely unfamiliar with (nothing weird about them, but I haven't worked with them before today).
What I need to do is update all the plugins and the core, and after it's done fix or rollback any introduced bugs. Thing is, I don't have shell access and I don't have access to a home directory on the server, so I can't automate a lot, or I don't know how to automate anything that will run tests or the like after every update to make sure that nothing is broken.
These are fairly large sites, so there are a lot of places bugs can hide. Is there a recommended procedure for this? Or is there a way that I can pretty well reliably catch any new bugs introduced?
I'm not worried about temporary errors, because this is a staging environment, but I do want comprehensive knowledge that nothing is busted. I should have access to error_log files, but I'm not 100% sure I do yet, and I haven't seen any.