php – “会话开始后无法设置会话ID.”同时测试表单

当测试提交表单时,它会抛出异常：

Uncaught PHP Exception LogicException: "Cannot set session ID after the session has started."

我正在使用Symfony 2.6.4.我找不到有关此错误消息的任何有用信息.该测试不久前完成了.

class ControllerTest extends WebTestCase
{
    public $client = null;
    public $route = 'home/';

    /**
     * @var DoctrineORMEntityManager
     */
    public $em;

    public function setUp()
    {
        self::bootKernel();
        $this->client = static::createClient();

        $this->em = static::$kernel->getContainer()
            ->get('doctrine')
            ->getManager()
        ;
    }

    public function logIn($role = 'admin')
    {
        if ($role === 'admin') {
            $userId = 20;
        } elseif ($role === 'user') {
            $userId = 29;
        }
        $user = $this->em->getRepository('AcmeDemoBundleEntityUser')->find($userId);

        $session = $this->client->getContainer()->get('session');

        $firewall = 'main';
        $token = new UsernamePasswordToken($user,$user->getPassword(),$firewall);
        $session->set('_security_'.$firewall,serialize($token));
        $session->save();

        $cookie = new Cookie($session->getName(),$session->getId());
        $this->client->getCookieJar()->set($cookie);
    }

    public function getFormData($valid = true)
    {
        //function to generate (in)valid formdata
    }

    public function getFormRequest($data,$url)
    {
        return $this->client->request(
            'POST',$url,$data,[],[
                'CONTENT_TYPE'          => 'application/json','HTTP_X-Requested-With' => 'XMLHttpRequest',]
        );
    }

    //works OK
    public function testNewScenario()
    {
        $url = $this->baseurl . 'new';
        $this->logIn('admin');

        $crawler = $this->client->request('GET',$url);
        $this->assertEquals(200,$this->client->getResponse()->getStatusCode(),"Unexpected HTTP status code for GET " . $url);
    }

    public function testValidNewScenario()
    {
        $this->logIn('admin');

        $validData = $this->getFormData(true);

        //this function throws the exception
        $this->getFormRequest($validData,$this->baseurl);

        $this->assertEquals(200,"Unexpected HTTP status code for POST " . $this->baseurl);
    }

}

这是我的config_test.yml的相关部分：

framework:
    test: ~
    session:
        storage_id: session.storage.mock_file
    profiler:
        collect: false

这是怎么回事？