Doctrine2 isolation of tests

Client.php

<?php
namespace Company\SecretBundle\Test;

use Doctrine\DBAL\Connection;
use Symfony\Bundle\FrameworkBundle\Client as BaseClient;
use Symfony\Component\HttpFoundation\File\File;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\KernelInterface;
use Symfony\Component\HttpKernel\TerminableInterface;

/**
 * @property KernelInterface $kernel
 * @property Response $response
 */
class Client extends BaseClient
{
    /** @var bool */
    private $requested = false;

    /**
     * @param string $method
     * @param string $uri
     * @param array $parameters
     * @param File[] $files
     * @param array $server
     * @param string|null $content
     * @param bool $changeHistory
     * @return Response
     */
    public function request(
        $method,
        $uri,
        array $parameters = array(),
        array $files = array(),
        array $server = array(),
        $content = null,
        $changeHistory = true
    ) {
        parent::request($method, $uri, $parameters, $files, $server, $content, $changeHistory);

        return $this->response;
    }

    /**
     * {@inheritDoc}
     */
    protected function doRequest($request)
    {
        /* @var $connection Connection */
        $connection = $this->getContainer()->get('doctrine.dbal.default_connection');

        if ($this->requested) {
            $this->kernel->shutdown();
            $this->kernel->boot();
        }

        $this->setConnection($connection);
        $this->requested = true;
        $response = $this->kernel->handle($request);

        if ($this->kernel instanceof TerminableInterface) {
            $this->kernel->terminate($request, $response);
        }

        return $response;
    }

    /**
     * @link http://alexandre-salome.fr/blog/Symfony2-Isolation-Of-Tests
     * @param Connection $connection
     */
    private function setConnection(Connection $connection)
    {
        $container = $this->getContainer();
        $eventManager = $connection->getEventManager();
        $oldListeners = $eventManager->getListeners();
        $newListeners = $container
            ->get('doctrine.dbal.default_connection')
            ->getEventManager()
            ->getListeners()
        ;

        // The connection instance contains also the event manager instance.
        // So replacing the connection means that all listeners are also replaced
        // thus it's needed to replace the old listeners with the listeners registered in the new container.
        foreach ($oldListeners as $event => $listeners) {
            foreach ($listeners as $listener) {
                $eventManager->removeEventListener($event, $listener);
            }
        }

        foreach ($newListeners as $event => $listeners) {
            foreach ($listeners as $listener) {
                $eventManager->addEventListener($event, $listener);
            }
        }

        $container->set('doctrine.dbal.default_connection', $connection);
    }
}