mkdir /tmp/test
cd /tmp/test
cat <<EOF > test.php
<?php
require dirname( __FILE__ ) . '/bar.php';
EOF
composer require mediawiki/mediawiki-codesniffer
vendor/bin/phpcs --standard=vendor/mediawiki/mediawiki-codesniffer/MediaWiki/ruleset.xml test.php

FILE: /tmp/test/test.php
---------------------------------------------------------------------------
FOUND 1 ERROR AFFECTING 1 LINE
---------------------------------------------------------------------------
 2 | ERROR | [x] Use __DIR__ constant instead of calling dirname(__FILE__)
---------------------------------------------------------------------------
PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
---------------------------------------------------------------------------