DroneForPHP is a tool to generate configuration files for drone.io, a continuous integration tool for PHP that uses Docker to run third-party software for code testing.
This site curates a list of that software that the author finds useful in his projects, and incorporates a tool to generate a drone configuration file (known as a .drone.yml file) to use that software.
For installation instructions for drone.io, see the official drone.io guide, here.
There are plenty of other code quality tools available, which may be more appropriate for your requirements. However, this tool is based on the PHP tools I find helpful and use.
The whole of DroneForPHP is hosted on github under MIT licence.