PHPCS rules for working with Magento
These code sniffer rules were created from the standards listed at the location below:
Magento 2 PHP Coding Standards
The ruleset.xml file should be placed in a "Mage" folder under your PHPCS Standards folder. I was able to find the location of the coding standards by running the following command:
cd $(dirname `which phpcs`)/../lib/php/PHP/CodeSniffer/Standards
If that does not work, you could find the location by calling:
cd $(dirname `which phpcs`)/../share/php/PHP/CodeSniffer/Standards