In order to perform the kata, first of all you will need to install all of the dependencies. This can be done using composer (standing from the "php" directory")
wget http://getcomposer.org/composer.phar
php composer.phar installNext, to execute the unit tests you need run this from the php directory
php bin/phpunit
When running the tests a coverage report should be generated automatically in simple text format and html report.
If you want to visualize it from the browser you can open
open coverage/report/index.html
in a browser after running the tests.
Enjoy