Testing upgrade to PHP 7 I have upgraded to PHP 7.1 on my local dev environment and my Drupal 7.59 site with CiviCRM 5.1.2 seems to be working just fine. I can't find any issues. I am wondering if there is a way in the CLI to check the compatibility of all enabled contrib modules or if I need to look each one up and/or just test extensively to see if anything isn't working.
At this point assuming your site doesnt make use of extra modules, you can likely assume 7.x php works fine. I have found in numerous sites in the last few months that moving to php7 went fine and most php 7 were squashed in popular D7 modules in the last year or two.

If you have alot of custom modules you could try running a php 7 linter from github to check modules for php7 related issues, rather than trying to live-test drupal itself.

Something such as this github repo:
https://github.com/wimg/PHPCompatibility