Easily Inject authenticated Symfony User objects into functional test

MyWebTestCase.php

<?php

use Liip\FunctionalTestBundle\Test\WebTestCase;
use Symfony\Component\HttpKernel\Profiler\Profiler;
use Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken;
use Symfony\Component\Security\Core\User\UserInterface;

/**
 * @group functional
 */
class MyWebTestCase extends WebTestCase
{
    abstract protected function getCurrentUser();

    /**
     * @param string $firewallName
     * @param array $options
     * @param array $server
     * @return Symfony\Component\BrowserKit\Client
     */
    protected function createClientWithAuthentication($firewallName, array $options = array(), array $server = array())
    {
        /* @var $client \Symfony\Component\BrowserKit\Client */
        $client = $this->createClient($options, $server);
        // has to be set otherwise "hasPreviousSession" in Request returns false.
        $client->getCookieJar()->set(new \Symfony\Component\BrowserKit\Cookie(session_name(), true));
        
        /* @var $user UserInterface */
        $user = $this->getCurrentUser();
        
        $token = new UsernamePasswordToken($user, null, $firewallName, $user->getRoles());
        self::$kernel->getContainer()->get('session')->set('_security_' . $firewallName, serialize($token));
        
        return $client;
    }
}