This is based on PSR-12 and my personal preferences. It's also based on AlexHowansky's work on ork-phpcs and other phpcs repos.
Source lives in src.
Namespace prefix is \Outsanity\ProjectOrLibrary\, so projects or librarys can
be used side-by-side if the need arises.
Unit tests live in tests.
Test namespace prefix is \Outsanity\ProjectOrLibrary\Tests\, with the
understanding that they will not be imported between projects.