title: How to check if a PHP project works well with a new PHP Version
body: <p>Is there a <strong>good</strong> way to test if a PHP project works well with a new version of PHP?
  Lets say we have a project developed under PHP 5.0 and want to run it now with PHP 5.4. The project have no unit tests or something like that.</p>
  
  <p>Just run it with PHP 5.4 and click around to see if there are errors is not save enough.</p>