Test session service provider with routes that does not use session

src/Silex/Provider/SessionServiceProvider.php

@@ -103,7 +103,8 @@ class SessionServiceProvider implements ServiceProviderInterface
             return;
         }
 
-        if ($session = $event->getRequest()->getSession()) {
+        $session = $event->getRequest()->getSession();
+        if ($session && $session->isStarted()) {
             $session->save();
 
             $params = session_get_cookie_params();

tests/Silex/Tests/Provider/SessionServiceProviderTest.php

@@ -14,8 +14,7 @@ namespace Silex\Tests\Provider;
 use Silex\Application;
 use Silex\WebTestCase;
 use Silex\Provider\SessionServiceProvider;
-
-use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpKernel\Client;
 
 /**
  * SessionProvider test cases.
@@ -77,4 +76,32 @@ class SessionServiceProviderTest extends WebTestCase
 
         return $app;
     }
+
+    public function testWithRoutesThatDoesNotUseSession()
+    {
+        $app = new Application();
+
+        $app->register(new SessionServiceProvider(), array(
+            'session.test' => true,
+        ));
+
+        $app->get('/', function () {
+            return 'A welcome page.';
+        });
+
+        $app->get('/robots.txt', function () {
+            return 'Informations for robots.';
+        });
+
+        $app['debug'] = true;
+        $app['exception_handler']->disable();
+
+        $client = new Client($app);
+
+        $client->request('get', '/');
+        $this->assertEquals('A welcome page.', $client->getResponse()->getContent());
+
+        $client->request('get', '/robots.txt');
+        $this->assertEquals('Informations for robots.', $client->getResponse()->getContent());
+    }
 }