Did you happen to see something like this while running your phpunit functional or integration tests?
[Semantical Error] The annotation "@Sensio\Bundle\FrameworkExtraBundle\Configuration\Route" ... does not exist, or could not be auto-loaded.
[Semantical Error] The annotation "@Symfony\Component\Validator\Constraints\NotBlank" ... does not exist, or could not be auto-loaded.
If so, you could be coming across an autoloader problem.
How do you fix this? Well, you want to autoload, of course.
How do I autoload?
I would assume you have a bootstrap file configured for php. All you have to do is point the loader to the correct vendor autoload.php file, register it, and you should be golden.
$loader = require '/../vendor/autoload.php'; // YMMV, this may be somewhere else for you. Doctrine\Common\Annotations\AnnotationRegistry::registerLoader([$loader, 'loadClass']);