Login user on eZPublish 5 with Symfony2

gistfile1.php

$userProvider = new Provider( $this->getRepository() );

$user = $userProvider->loadUserByUsername( __LOGIN_USER__ );

$token = new UsernamePasswordToken($user, null, "ezpublish_front", $user->getRoles());
$this->get("security.context")->setToken($token);

//now dispatch the login event
$request = $this->get("request");
$event = new InteractiveLoginEvent($request, $token);
$this->get("event_dispatcher")->dispatch("security.interactive_login", $event);