My server is updating to PHP 5.6 next week. I manage about 30 WordPress websites. I looked for a plugin that would check if any of the code throughout the other plugins and theme would break with the update. I tried using the log deprecated notices plugin but it didn't seem very conclusive as to whether one of the deprecated calls would actually break the site or not ( or maybe it's impossible to know which things would actually break the site compared to those which would be just not ideal )
What is the best way of doing this? I know I can manually change the sites on Cpanel one at a time ahead of the global update but I was hoping for something more efficient.
Generally speaking all themes and plugins ( and wp cores ) are at their latest versions but it's possible some of the latest versions of a few of the plugins may be older than is ideal.