Some extensions, like GraphViz, have a "autoload" key with "files" in composer.json.
The file there is the entry point for the extension, which is automatically loaded on each request.
The entry point checks for defined( 'MEDIAWIKI' ) and die when it is not set.
It is not set when running parallel-lint or phpcs over "composer test".
Needs some ideas to find more of this extensions and find a way to handle this. phpcs should run on all repository where it is set in composer.json