We should do our standard PHP test and review of functionality. But with this site, there is a single sign-on requiring the client do an additional layer of testing.
The client needs to test this in the opposite direction. Since the SSO login plugin is the most important thing to test and we can’t test it because we aren’t part of their internal network (and use the special login URL). So from their end, they need to make sure:
- they logged out of the site
- they need to click the Preview PHP 7.4 link
- Make sure they get redirected to their login
- Make sure they can log in normally and use the site
Only the client can test the above. What you will be testing is the overall site functionality on the new PHP version as normal.