A few days ago Toon Verwerft gave an uncon talk at PHP Benelux Conference about a new code quality checking tool he has been developing. It's called GrumPHP. It can automatically perform various code quality checks when you try to commit some code.
Sick and tired of defending code quality over and over again? GrumPHP will do it for you! This composer plugin will register some git hooks in your package repository. When somebody commits changes, GrumPHP will run some tests on the committed code. If the tests fail, you won't be able to commit your changes. This handy tool will not only improve your codebase, it will also teach your co-workers to write better code following the best practices you've determined as a team.
The slides of Toon's talk can be found on speakerdeck.