If someone wants to contribute:
This projects follows PHP coding standards, so pull requests need to execute the Fabien Potencier's PHP-CS-Fixer and Marc Morera's PHP-Formatter. Furthermore, if the PR creates some not-PHP file remember that you have to put the license header manually.
$ vendor/bin/php-cs-fixer fix
$ vendor/bin/php-cs-fixer fix --config-file .phpspec_cs
$ vendor/bin/php-formatter formatter:use:sort
$ vendor/bin/php-formatter formatter:header:fix
There is also a policy for contributing to this project. Pull requests must be explained step by step to make the review process easy in order to accept and merge them. New methods or code improvements must come paired with PHPSpec tests.