make the stopwatch service always available

Previously, one had to be careful to check if the debug.stopwatch
service was available before using it. Otherwise, the application
would break in the prod environment.

Author: xabbuh

Resources/config/twig.xml

@@ -92,6 +92,7 @@
         <service id="twig.extension.debug.stopwatch" class="%twig.extension.debug.stopwatch.class%" public="false">
             <tag name="twig.extension" />
             <argument type="service" id="debug.stopwatch" on-invalid="ignore" />
+            <argument>%kernel.debug%</argument>
         </service>
 
         <service id="twig.extension.expression" class="%twig.extension.expression.class%" public="false">

Tests/DependencyInjection/TwigExtensionTest.php

@@ -179,6 +179,37 @@ public function getFormats()
         );
     }
 
+    /**
+     * @dataProvider stopwatchExtensionAvailabilityProvider
+     */
+    public function testStopwatchExtensionAvailability($debug, $stopwatchEnabled, $expected)
+    {
+        $container = $this->createContainer();
+        $container->setParameter('kernel.debug', $debug);
+        if ($stopwatchEnabled) {
+            $container->register('debug.stopwatch', 'Symfony\Component\Stopwatch\Stopwatch');
+        }
+        $container->registerExtension(new TwigExtension());
+        $container->loadFromExtension('twig', array());
+        $this->compileContainer($container);
+
+        $tokenParsers = $container->get('twig.extension.debug.stopwatch')->getTokenParsers();
+        $stopwatchIsAvailable = new \ReflectionProperty($tokenParsers[0], 'stopwatchIsAvailable');
+        $stopwatchIsAvailable->setAccessible(true);
+
+        $this->assertSame($expected, $stopwatchIsAvailable->getValue($tokenParsers[0]));
+    }
+
+    public function stopwatchExtensionAvailabilityProvider()
+    {
+        return array(
+            'debug-and-stopwatch-enabled' => array(true, true, true),
+            'only-stopwatch-enabled' => array(false, true, false),
+            'only-debug-enabled' => array(true, false, false),
+            'debug-and-stopwatch-disabled' => array(false, false, false),
+        );
+    }
+
     private function createContainer()
     {
         $container = new ContainerBuilder(new ParameterBag(array(