Fix missing _route parameter notice in RouterListener logging case

src/Symfony/Component/HttpKernel/EventListener/RouterListener.php

@@ -103,7 +103,7 @@ class RouterListener implements EventSubscriberInterface
             }
 
             if (null !== $this->logger) {
-                $this->logger->info(sprintf('Matched route "%s" (parameters: %s)', $parameters['_route'], $this->parametersToString($parameters)));
+                $this->logger->info(sprintf('Matched route "%s" (parameters: %s)', isset($parameters['_route']) ? $parameters['_route'] : 'n/a', $this->parametersToString($parameters)));
             }
 
             $request->attributes->add($parameters);

src/Symfony/Component/HttpKernel/Tests/EventListener/RouterListenerTest.php

@@ -120,4 +120,34 @@ class RouterListenerTest extends \PHPUnit_Framework_TestCase
 
         $this->assertEquals('GET', $context->getMethod());
     }
+
+    /**
+     * @dataProvider getLoggingParameterData
+     */
+    public function testLoggingParameter($parameter, $log)
+    {
+        $requestMatcher = $this->getMock('Symfony\Component\Routing\Matcher\RequestMatcherInterface');
+        $requestMatcher->expects($this->once())
+          ->method('matchRequest')
+          ->will($this->returnValue($parameter));
+
+        $logger = $this->getMock('Psr\Log\LoggerInterface');
+        $logger->expects($this->once())
+          ->method('info')
+          ->with($this->equalTo($log));
+
+        $kernel = $this->getMock('Symfony\Component\HttpKernel\HttpKernelInterface');
+        $request = Request::create('http://localhost/');
+
+        $listener = new RouterListener($requestMatcher, new RequestContext(), $logger, $this->requestStack);
+        $listener->onKernelRequest(new GetResponseEvent($kernel, $request, HttpKernelInterface::MASTER_REQUEST));
+    }
+
+    public function getLoggingParameterData()
+    {
+        return array(
+            array(array('_route' => 'foo'), 'Matched route "foo".'),
+            array(array(), 'Matched route "n/a".'),
+        );
+    }
 }