在Symfony 2.6上测试多个请求的隔离

我的项目使用Symfony 2.6。我正在尝试隔离我的测试,以便不在我的数据库上提交任何更改。

我只需要一个请求就可以隔离我的测试。但是当有很多这样的时候,它就不起作用了,我也找不到原因。有什么想法吗?

这是我的testController代码:

use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;

class RequestControllerTest extends WebTestCase{

    protected $client;
    protected $entityManager;

    protected function setUp(){
        parent::setUp();
        $this->client = static::createClient();
        $this->entityManager = $this->client->getContainer()->get('doctrine')->getManager();
        $this->entityManager->beginTransaction();
    }

    protected function tearDown(){
        parent::tearDown();
        $this->entityManager->rollback();
        $this->entityManager->close();
    }

    // This test is working just fine : the request isn't deleted from database at the end
    public function testIsolationOK(){
       $this->client->request('DELETE', self::WEB_SERVICES_EXISTING_REQUEST_URL);
       $this->client->request('GET', self::WEB_SERVICES_EXISTING_REQUEST_URL);           
    }

    // But this one isn't working : the request is deleted from database at the end
    public function testIsolationNOK(){
       $this->client->request('GET', self::WEB_SERVICES_EXISTING_REQUEST_URL);
       $this->client->request('DELETE', self::WEB_SERVICES_EXISTING_REQUEST_URL);
    }

}