Setup Install `phpcs`, and the moodlehq coding standards, globally: composer global require moodlehq/moodle-cs Ensure that your global vendor binaries directory is in your $PATH as noted at https://getcomposer.org/doc/03-cli.md#global - this will depend on your installation, but usually it's a case of updating your .bashrc or .zshrc (or whatever shell you use) to add: export PATH=~/.composer/vendor/bin:$PATH Test Go to your moodle instance's root folder. Make sure you're using the correct nodejs version and that grunt-cli is installed. Assuming you have nvm : nvm install npm i Ensure you do not already have the phpcs.xml or .phpcs.xml files: rm phpcs.xml .phpcs.xml Remove any default standard for phpcs: phpcs --config-delete default_standard Run phpcs against: 4.0, 4.1, master: course/format/classes : 3.11: admin/antiviruses.php # 4.0+ phpcs -sp course/format/classes # 3.11: phpcs -sp admin/antiviruses.php Confirm that there were some warnings about Squiz.Operators.ValidLogicalOperators.NotAllowed (which is not allowed) Note: There are also some other warnings Run phpcs against an external file, for example lib/zipstream : phpcs -sp lib/zipstream Confirm that loads of Moodle-specific errors/warnings are shown (e.g. header) (At this point we don't know how to ignore it) Generate the ignorefile: npx grunt ignorefiles Run phpcs against an external file again, for example lib/zipstream : phpcs -sp lib/zipstream Confirm that there was no output at all Run phpcs with increased verbosity to check that files are appropriately ignored: phpcs -spvv lib/zipstream Confirm that the file was loaded: (You will see something similar to the following) Processing ruleset /path/to/your/moodle/phpcs.xml Confirm that the Moodle ruleset was then used: (The following will be in the output) Processing rule "moodle" Confirm that a number of global ignore patterns were added, including lib/zipstream : (The following will be in the output) => added global absolute ignore pattern: lib/zipstream/ Remove the Moodle standard but ensure that phpcs is still installed composer global remove moodlehq/moodle-cs composer global require squizlabs/php_codesniffer Run phpcs on a file again phpcs index.php Confirm that it complained that no sniffs were available : ERROR: No sniffs were registered   Run "phpcs --help" for usage information Install the moodlehq coding standards and my stricter standards, globally: composer global remove squizlabs/php_codesniffer composer global require moodlehq/moodle-cs andrewnicols/moodle-cs-strict Fix a standard Moodle file using the normal Moodle standard: phpcbf lib/externallib.php Have git stage it so you can detect the changes more easily git add lib/externallib.php Now create a new .phpcs.xml file with your new, stricter, configuration: <?xml version="1.0" encoding="UTF-8"?> <ruleset name="MoodleCore"> <rule ref="./phpcs.xml"/> <rule ref="MoodleStrict"/> </ruleset> Add to your local git ignore: echo .phpcs.xml >> .git/info/exclude Run phpcbf against the file again: phpcbf -sp lib/externallib.php Compare the changes: git diff Confirm that the diff showed additional changes to the code Resetting after the test Remove the local configuration rm .phpcs.xml Reset git git reset git checkout . git clean -f