Logging user into a Symfony app in Behat

AuthenticationContext.php

<?php

namespace Acme\Context;

use Acme\MyApp\User;
use Behat\MinkExtension\Context\RawMinkContext;
use Behat\Symfony2Extension\Context\KernelAwareInterface;
use Doctrine\ORM\EntityManager;
use HWI\Bundle\OAuthBundle\Security\Core\Authentication\Token\OAuthToken;
use Symfony\Component\HttpKernel\KernelInterface;

class LeaveRequestContext extends RawMinkContext implements KernelAwareInterface
{
    /**
     * @var KernelInterface
     */
    private $kernel;

    /**
     * @var User
     */
    private $user;

    /**
     * @param KernelInterface $kernel
     */
    public function setKernel(KernelInterface $kernel)
    {
        $this->kernel = $kernel;
    }

    /**
     * @Given /^I am logged in$/
     */
    public function iAmLoggedIn()
    {
        $this->user = $this->createUser();

        $token = $this->getOAuthToken($this->user, array('ROLE_USER'));

        $firewall = 'secured_area';
        $session = $this->kernel->getContainer()->get('session');
        $session->set('_security_'.$firewall, serialize($token));
        $session->save();

        $this->getSession()->setCookie($session->getName(), $session->getId());
    }

    /**
     * @return User
     */
    private function createUser()
    {
        $user = new User();
        $user->setName('Kuba');

        $em = $this->getEntityManager();
        $em->persist($user);
        $em->flush();

        return $user;
    }

    /**
     * @param mixed $user
     * @param array $roles
     *
     * @return OAuthToken
     */
    private function getOAuthToken($user, array $roles)
    {
        $token  = new OAuthToken('a-random-access-token', $roles);
        $token->setResourceOwnerName('google');
        $token->setUser($user);

        return $token;
    }

    /**
     * @return EntityManager
     */
    private function getEntityManager()
    {
        return $this->kernel->getContainer()->get('doctrine')->getManager();
    }
}