feature #13378 lazy-load fragment renderers (fabpot)

This PR was merged into the 2.7 branch.

Discussion
----------

lazy-load fragment renderers

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Now that we have more fragment renderers (inline, hinclude, esi, and ssi), it's a waste of time to load them all for every single requests; actually, most of the time, we load them for nothing.

So, like we did for event listeners, I propose to lazy-load them.

I've also move the classes to the HttpKernel component as the corresponding classes for the lazy-loading of listeners were moved to the EventDispatcher component a while ago to make them reusable outside of the Symfony2 context.

Last, but not the least, I've named the class with a `LazyLoading` prefix instead of the usual `ContainerAware` as I think it conveys the goal much better. I'd like to rename the other ones as well when it makes sense.

Commits
-------

2be8b6e [TwigBundle] optimized the hinclude fragement renderer when only Twig is used
6148652 [FrameworkBundle] removed obsolete ContainerAwareHIncludeFragmentRenderer class
e620cbf lazy-load fragment renderers

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/FragmentRendererPass.php

@@ -11,6 +11,8 @@
 
 namespace Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler;
 
+trigger_error('The '.__NAMESPACE__.'\FragmentRendererPass class is deprecated since version 2.7 and will be removed in 3.0. Use Symfony\Component\HttpKernel\DependencyInjection\FragmentRendererPass instead.', E_USER_DEPRECATED);
+
 use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
@@ -19,6 +21,8 @@ use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
  * Adds services tagged kernel.fragment_renderer as HTTP content rendering strategies.
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since version 2.7, to be removed in 3.0. Use Symfony\Component\HttpKernel\DependencyInjection\FragmentRendererPass instead.
  */
 class FragmentRendererPass implements CompilerPassInterface
 {

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

@@ -539,6 +539,11 @@ class FrameworkExtension extends Extension
             $container->setAlias('templating', 'templating.engine.delegating');
         }
 
+        $container->getDefinition('fragment.renderer.hinclude')
+            ->addTag('kernel.fragment_renderer', array('alias' => 'hinclude'))
+            ->replaceArgument(0, new Reference('templating'))
+        ;
+
         // configure the PHP engine if needed
         if (in_array('php', $config['engines'], true)) {
             $loader->load('templating_php.xml');

src/Symfony/Bundle/FrameworkBundle/Fragment/ContainerAwareHIncludeFragmentRenderer.php

@@ -11,6 +11,8 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Fragment;
 
+trigger_error('The '.__NAMESPACE__.'\ContainerAwareHIncludeFragmentRenderer class is deprecated since version 2.7 and will be removed in 3.0. Use Symfony\Bundle\FrameworkBundle\Fragment\HIncludeFragmentRenderer instead.', E_USER_DEPRECATED);
+
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\UriSigner;
@@ -20,6 +22,8 @@ use Symfony\Component\HttpKernel\Fragment\HIncludeFragmentRenderer;
  * Implements the Hinclude rendering strategy.
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since version 2.7, to be removed in 3.0. Use Symfony\Bundle\FrameworkBundle\Fragment\HIncludeFragmentRenderer instead.
  */
 class ContainerAwareHIncludeFragmentRenderer extends HIncludeFragmentRenderer
 {

src/Symfony/Bundle/FrameworkBundle/FrameworkBundle.php

@@ -28,13 +28,13 @@ use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\ContainerBuilder
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\CompilerDebugDumpPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\TranslationExtractorPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\TranslationDumperPass;
-use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\FragmentRendererPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\SerializerPass;
 use Symfony\Component\Debug\ErrorHandler;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Compiler\PassConfig;
 use Symfony\Component\DependencyInjection\Scope;
 use Symfony\Component\EventDispatcher\DependencyInjection\RegisterListenersPass;
+use Symfony\Component\HttpKernel\DependencyInjection\FragmentRendererPass;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Bundle\Bundle;
 

src/Symfony/Bundle/FrameworkBundle/Resources/config/fragment_renderer.xml

@@ -5,9 +5,9 @@
     xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
 
     <parameters>
-        <parameter key="fragment.handler.class">Symfony\Component\HttpKernel\Fragment\FragmentHandler</parameter>
+        <parameter key="fragment.handler.class">Symfony\Component\HttpKernel\DependencyInjection\LazyLoadingFragmentHandler</parameter>
         <parameter key="fragment.renderer.inline.class">Symfony\Component\HttpKernel\Fragment\InlineFragmentRenderer</parameter>
-        <parameter key="fragment.renderer.hinclude.class">Symfony\Bundle\FrameworkBundle\Fragment\ContainerAwareHIncludeFragmentRenderer</parameter>
+        <parameter key="fragment.renderer.hinclude.class">Symfony\Component\HttpKernel\Fragment\HIncludeFragmentRenderer</parameter>
         <parameter key="fragment.renderer.hinclude.global_template"></parameter>
         <parameter key="fragment.renderer.esi.class">Symfony\Component\HttpKernel\Fragment\EsiFragmentRenderer</parameter>
         <parameter key="fragment.path">/_fragment</parameter>
@@ -15,28 +15,27 @@
 
     <services>
         <service id="fragment.handler" class="%fragment.handler.class%">
-            <argument type="collection" />
+            <argument type="service" id="service_container" />
             <argument>%kernel.debug%</argument>
             <argument type="service" id="request_stack" />
         </service>
 
         <service id="fragment.renderer.inline" class="%fragment.renderer.inline.class%">
-            <tag name="kernel.fragment_renderer" />
+            <tag name="kernel.fragment_renderer" alias="inline" />
             <argument type="service" id="http_kernel" />
             <argument type="service" id="event_dispatcher" />
             <call method="setFragmentPath"><argument>%fragment.path%</argument></call>
         </service>
 
         <service id="fragment.renderer.hinclude" class="%fragment.renderer.hinclude.class%">
-            <tag name="kernel.fragment_renderer" />
-            <argument type="service" id="service_container" />
+            <argument /> <!-- templating or Twig service -->
             <argument type="service" id="uri_signer" />
             <argument>%fragment.renderer.hinclude.global_template%</argument>
             <call method="setFragmentPath"><argument>%fragment.path%</argument></call>
         </service>
 
         <service id="fragment.renderer.esi" class="%fragment.renderer.esi.class%">
-            <tag name="kernel.fragment_renderer" />
+            <tag name="kernel.fragment_renderer" alias="esi" />
             <argument type="service" id="esi" on-invalid="null" />
             <argument type="service" id="fragment.renderer.inline" />
             <argument type="service" id="uri_signer" />
@@ -44,7 +43,7 @@
         </service>
 
         <service id="fragment.renderer.ssi" class="Symfony\Component\HttpKernel\Fragment\SsiFragmentRenderer">
-            <tag name="kernel.fragment_renderer" />
+            <tag name="kernel.fragment_renderer" alias="ssi" />
             <argument type="service" id="ssi" on-invalid="null" />
             <argument type="service" id="fragment.renderer.inline" />
             <argument type="service" id="uri_signer" />

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Compiler/LegacyFragmentRendererPassTest.php

@@ -0,0 +1,114 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\FrameworkBundle\Tests\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\Reference;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\FragmentRendererPass;
+
+class LegacyFragmentRendererPassTest extends \PHPUnit_Framework_TestCase
+{
+    public function setUp()
+    {
+        $this->iniSet('error_reporting', -1 & ~E_USER_DEPRECATED);
+    }
+
+    /**
+     * Tests that content rendering not implementing FragmentRendererInterface
+     * trigger an exception.
+     *
+     * @expectedException \InvalidArgumentException
+     */
+    public function testContentRendererWithoutInterface()
+    {
+        // one service, not implementing any interface
+        $services = array(
+            'my_content_renderer' => array(),
+        );
+
+        $definition = $this->getMock('Symfony\Component\DependencyInjection\Definition');
+        $definition->expects($this->atLeastOnce())
+            ->method('getClass')
+            ->will($this->returnValue('stdClass'));
+
+        $builder = $this->getMock(
+            'Symfony\Component\DependencyInjection\ContainerBuilder',
+            array('hasDefinition', 'findTaggedServiceIds', 'getDefinition')
+        );
+        $builder->expects($this->any())
+            ->method('hasDefinition')
+            ->will($this->returnValue(true));
+
+        // We don't test kernel.fragment_renderer here
+        $builder->expects($this->atLeastOnce())
+            ->method('findTaggedServiceIds')
+            ->will($this->returnValue($services));
+
+        $builder->expects($this->atLeastOnce())
+            ->method('getDefinition')
+            ->will($this->returnValue($definition));
+
+        $pass = new FragmentRendererPass();
+        $pass->process($builder);
+    }
+
+    public function testValidContentRenderer()
+    {
+        $services = array(
+            'my_content_renderer' => array(),
+        );
+
+        $renderer = $this->getMock('Symfony\Component\DependencyInjection\Definition');
+        $renderer
+            ->expects($this->once())
+            ->method('addMethodCall')
+            ->with('addRenderer', array(new Reference('my_content_renderer')))
+        ;
+
+        $definition = $this->getMock('Symfony\Component\DependencyInjection\Definition');
+        $definition->expects($this->atLeastOnce())
+            ->method('getClass')
+            ->will($this->returnValue('Symfony\Bundle\FrameworkBundle\Tests\DependencyInjection\Compiler\RendererService'));
+
+        $builder = $this->getMock(
+            'Symfony\Component\DependencyInjection\ContainerBuilder',
+            array('hasDefinition', 'findTaggedServiceIds', 'getDefinition')
+        );
+        $builder->expects($this->any())
+            ->method('hasDefinition')
+            ->will($this->returnValue(true));
+
+        // We don't test kernel.fragment_renderer here
+        $builder->expects($this->atLeastOnce())
+            ->method('findTaggedServiceIds')
+            ->will($this->returnValue($services));
+
+        $builder->expects($this->atLeastOnce())
+            ->method('getDefinition')
+            ->will($this->onConsecutiveCalls($renderer, $definition));
+
+        $pass = new FragmentRendererPass();
+        $pass->process($builder);
+    }
+}
+
+class RendererService implements \Symfony\Component\HttpKernel\Fragment\FragmentRendererInterface
+{
+    public function render($uri, Request $request = null, array $options = array())
+    {
+    }
+
+    public function getName()
+    {
+        return 'test';
+    }
+}

src/Symfony/Bundle/FrameworkBundle/Tests/Fragment/LegacyContainerAwareHIncludeFragmentRendererTest.php

@@ -15,10 +15,12 @@ use Symfony\Bundle\FrameworkBundle\Tests\TestCase;
 use Symfony\Bundle\FrameworkBundle\Fragment\ContainerAwareHIncludeFragmentRenderer;
 use Symfony\Component\HttpFoundation\Request;
 
-class ContainerAwareHIncludeFragmentRendererTest extends TestCase
+class LegacyContainerAwareHIncludeFragmentRendererTest extends TestCase
 {
     public function testRender()
     {
+        $this->iniSet('error_reporting', -1 & ~E_USER_DEPRECATED);
+
         $container = $this->getMock('Symfony\Component\DependencyInjection\ContainerInterface');
         $container->expects($this->once())
             ->method('get')

src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/Controller/FragmentController.php

@@ -19,23 +19,7 @@ class FragmentController extends ContainerAware
 {
     public function indexAction(Request $request)
     {
-        $actions = $this->container->get('templating')->get('actions');
-
-        $html1 = $actions->render($actions->controller('TestBundle:Fragment:inlined', array(
-            'options' => array(
-                'bar' => new Bar(),
-                'eleven' => 11,
-            ),
-        )));
-
-        $html2 = $actions->render($actions->controller('TestBundle:Fragment:customformat', array('_format' => 'html')));
-
-        $html3 = $actions->render($actions->controller('TestBundle:Fragment:customlocale', array('_locale' => 'es')));
-
-        $request->setLocale('fr');
-        $html4 = $actions->render($actions->controller('TestBundle:Fragment:forwardlocale'));
-
-        return new Response($html1.'--'.$html2.'--'.$html3.'--'.$html4);
+        return $this->container->get('templating')->renderResponse('fragment.html.php', array('bar' => new Bar()));
     }
 
     public function inlinedAction($options, $_format)

src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/Resources/fragment.html.php

@@ -0,0 +1,14 @@
+<?php echo $this->get('actions')->render($this->get('actions')->controller('TestBundle:Fragment:inlined', array(
+            'options' => array(
+                'bar' => $bar,
+                'eleven' => 11,
+            ),
+        )));
+?>--<?php
+        echo $this->get('actions')->render($this->get('actions')->controller('TestBundle:Fragment:customformat', array('_format' => 'html')));
+?>--<?php
+        echo $this->get('actions')->render($this->get('actions')->controller('TestBundle:Fragment:customlocale', array('_locale' => 'es')));
+?>--<?php
+        $app->getRequest()->setLocale('fr');
+        echo $this->get('actions')->render($this->get('actions')->controller('TestBundle:Fragment:forwardlocale'));
+?>

src/Symfony/Bundle/TwigBundle/DependencyInjection/Compiler/ExtensionPass.php

@@ -13,6 +13,7 @@ namespace Symfony\Bundle\TwigBundle\DependencyInjection\Compiler;
 
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
 
 /**
  * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
@@ -41,6 +42,17 @@ class ExtensionPass implements CompilerPassInterface
 
         if ($container->has('fragment.handler')) {
             $container->getDefinition('twig.extension.httpkernel')->addTag('twig.extension');
+
+            // inject Twig in the hinclude service if Twig is the only registered templating engine
+            if (
+                !$container->hasParameter('templating.engines')
+                || array('twig') == $container->getParameter('templating.engines')
+            ) {
+                $container->getDefinition('fragment.renderer.hinclude')
+                    ->addTag('kernel.fragment_renderer', array('alias' => 'hinclude'))
+                    ->replaceArgument(0, new Reference('twig'))
+                ;
+            }
         }
 
         if ($container->has('request_stack')) {

src/Symfony/Component/HttpKernel/DependencyInjection/FragmentRendererPass.php

@@ -0,0 +1,73 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpKernel\DependencyInjection;
+
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+
+/**
+ * Adds services tagged kernel.fragment_renderer as HTTP content rendering strategies.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class FragmentRendererPass implements CompilerPassInterface
+{
+    private $handlerService;
+    private $rendererTag;
+
+    /**
+     * @param string $handlerService Service name of the fragment handler in the container
+     * @param string $rendererTag    Tag name used for fragments
+     */
+    public function __construct($handlerService = 'fragment.handler', $rendererTag = 'kernel.fragment_renderer')
+    {
+        $this->handlerService = $handlerService;
+        $this->rendererTag = $rendererTag;
+    }
+
+    public function process(ContainerBuilder $container)
+    {
+        if (!$container->hasDefinition($this->handlerService)) {
+            return;
+        }
+
+        $definition = $container->getDefinition($this->handlerService);
+        foreach ($container->findTaggedServiceIds($this->rendererTag) as $id => $tags) {
+            $def = $container->getDefinition($id);
+            if (!$def->isPublic()) {
+                throw new \InvalidArgumentException(sprintf('The service "%s" must be public as fragment renderer are lazy-loaded.', $id));
+            }
+
+            if ($def->isAbstract()) {
+                throw new \InvalidArgumentException(sprintf('The service "%s" must not be abstract as fragment renderer are lazy-loaded.', $id));
+            }
+
+            $refClass = new \ReflectionClass($container->getParameterBag()->resolveValue($def->getClass()));
+            $interface = 'Symfony\Component\HttpKernel\Fragment\FragmentRendererInterface';
+            if (!$refClass->implementsInterface($interface)) {
+                throw new \InvalidArgumentException(sprintf('Service "%s" must implement interface "%s".', $id, $interface));
+            }
+
+            foreach ($tags as $tag) {
+                if (!isset($tag['alias'])) {
+                    trigger_error(sprintf('Service "%s" will have to define the "alias" attribute on the "%s" tag as of Symfony 3.0.', $id, $this->fragmentTag), E_USER_DEPRECATED);
+
+                    // register the handler as a non-lazy-loaded one
+                    $definition->addMethodCall('addRenderer', array(new Reference($id)));
+                }
+
+                $definition->addMethodCall('addRendererService', array($tag['alias'], $id));
+            }
+        }
+    }
+}

src/Symfony/Component/HttpKernel/DependencyInjection/LazyLoadingFragmentHandler.php

@@ -0,0 +1,58 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpKernel\DependencyInjection;
+
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpKernel\Fragment\FragmentHandler;
+
+/**
+ * Lazily loads fragment renderers from the dependency injection container.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class LazyLoadingFragmentHandler extends FragmentHandler
+{
+    private $container;
+    private $rendererIds = array();
+
+    public function __construct(ContainerInterface $container, $debug = false, RequestStack $requestStack = null)
+    {
+        $this->container = $container;
+
+        parent::__construct(array(), $debug, $requestStack);
+    }
+
+    /**
+     * Adds a service as a fragment renderer.
+     *
+     * @param string $renderer The render service id
+     */
+    public function addRendererService($name, $renderer)
+    {
+        $this->rendererIds[$name] = $renderer;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function render($uri, $renderer = 'inline', array $options = array())
+    {
+        if (isset($this->rendererIds[$renderer])) {
+            $this->addRenderer($this->container->get($this->rendererIds[$renderer]));
+
+            unset($this->rendererIds[$renderer]);
+        }
+
+        return parent::render($uri, $renderer, $options);
+    }
+}

src/Symfony/Component/HttpKernel/Tests/DependencyInjection/FragmentRendererPassTest.php

@@ -9,11 +9,11 @@
  * file that was distributed with this source code.
  */
 
-namespace Symfony\Bundle\FrameworkBundle\Tests\DependencyInjection\Compiler;
+namespace Symfony\Component\HttpKernel\Tests\DependencyInjection;
 
-use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\HttpFoundation\Request;
-use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\FragmentRendererPass;
+use Symfony\Component\HttpKernel\DependencyInjection\FragmentRendererPass;
+use Symfony\Component\HttpKernel\Fragment\FragmentRendererInterface;
 
 class FragmentRendererPassTest extends \PHPUnit_Framework_TestCase
 {
@@ -27,13 +27,10 @@ class FragmentRendererPassTest extends \PHPUnit_Framework_TestCase
     {
         // one service, not implementing any interface
         $services = array(
-            'my_content_renderer' => array(),
+            'my_content_renderer' => array('alias' => 'foo'),
         );
 
         $definition = $this->getMock('Symfony\Component\DependencyInjection\Definition');
-        $definition->expects($this->atLeastOnce())
-            ->method('getClass')
-            ->will($this->returnValue('stdClass'));
 
         $builder = $this->getMock(
             'Symfony\Component\DependencyInjection\ContainerBuilder',
@@ -59,20 +56,25 @@ class FragmentRendererPassTest extends \PHPUnit_Framework_TestCase
     public function testValidContentRenderer()
     {
         $services = array(
-            'my_content_renderer' => array(),
+            'my_content_renderer' => array(array('alias' => 'foo')),
         );
 
         $renderer = $this->getMock('Symfony\Component\DependencyInjection\Definition');
         $renderer
             ->expects($this->once())
             ->method('addMethodCall')
-            ->with('addRenderer', array(new Reference('my_content_renderer')))
+            ->with('addRendererService', array('foo', 'my_content_renderer'))
         ;
 
         $definition = $this->getMock('Symfony\Component\DependencyInjection\Definition');
         $definition->expects($this->atLeastOnce())
             ->method('getClass')
-            ->will($this->returnValue('Symfony\Bundle\FrameworkBundle\Tests\DependencyInjection\Compiler\RendererService'));
+            ->will($this->returnValue('Symfony\Component\HttpKernel\Tests\DependencyInjection\RendererService'));
+        $definition
+            ->expects($this->once())
+            ->method('isPublic')
+            ->will($this->returnValue(true))
+        ;
 
         $builder = $this->getMock(
             'Symfony\Component\DependencyInjection\ContainerBuilder',
@@ -96,7 +98,7 @@ class FragmentRendererPassTest extends \PHPUnit_Framework_TestCase
     }
 }
 
-class RendererService implements \Symfony\Component\HttpKernel\Fragment\FragmentRendererInterface
+class RendererService implements FragmentRendererInterface
 {
     public function render($uri, Request $request = null, array $options = array())
     {

src/Symfony/Component/HttpKernel/Tests/DependencyInjection/LazyLoadingFragmentHandlerTest.php

@@ -0,0 +1,40 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpKernel\Tests\DependencyInjection;
+
+use Symfony\Component\HttpKernel\DependencyInjection\LazyLoadingFragmentHandler;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class LazyLoadingFragmentHandlerTest extends \PHPUnit_Framework_TestCase
+{
+    public function test()
+    {
+        $renderer = $this->getMock('Symfony\Component\HttpKernel\Fragment\FragmentRendererInterface');
+        $renderer->expects($this->once())->method('getName')->will($this->returnValue('foo'));
+        $renderer->expects($this->any())->method('render')->will($this->returnValue(new Response()));
+
+        $requestStack = $this->getMock('Symfony\Component\HttpFoundation\RequestStack');
+        $requestStack->expects($this->any())->method('getCurrentRequest')->will($this->returnValue(Request::create('/')));
+
+        $container = $this->getMock('Symfony\Component\DependencyInjection\ContainerInterface');
+        $container->expects($this->once())->method('get')->will($this->returnValue($renderer));
+
+        $handler = new LazyLoadingFragmentHandler($container, false, $requestStack);
+        $handler->addRendererService('foo', 'foo');
+
+        $handler->render('/foo', 'foo');
+
+        // second call should not lazy-load anymore (see once() above on the get() method)
+        $handler->render('/foo', 'foo');
+    }
+}