If you want to make a PHP package available that works on versions of PHP from 5.3 to 8.0, testing is a giant pain. There are versions of phpunit that work for each, but none that works for all. Additionally, the basic class names changed at some point in the past. Getting all of this to run on Travis, including running code coverage (but only once for each build!) was a complex series of trials, but I finally figured out the correct .travis.yml incantation, along with a magic test wrapper for aliasing classes