Add custom 404 and 500 error pages via ExceptionListener

- Create ExceptionListener that renders custom error templates in prod
- Skip in dev environment to keep Symfony debug pages
- 404: neo-brutalist page with large "404" text and return link
- 500: generic server error page with status code display
- Add 4 unit tests (dev skip, 404 render, 500 render, other HTTP codes)
- Register kernel.environment parameter for ExceptionListener

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config/services.yaml

@@ -34,6 +34,10 @@ services:
                     key: '%env(S3_ACCESS_KEY)%'
                     secret: '%env(S3_SECRET_KEY)%'
 
+    App\EventListener\ExceptionListener:
+        arguments:
+            $kernelEnvironment: '%kernel.environment%'
+
     App\Twig\ViteAssetExtension:
         arguments:
             $manifest: '%kernel.project_dir%/public/build/.vite/manifest.json'

src/EventListener/ExceptionListener.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace App\EventListener;
+
+use Symfony\Component\EventDispatcher\Attribute\AsEventListener;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;
+use Symfony\Component\HttpKernel\KernelEvents;
+use Twig\Environment;
+
+#[AsEventListener(event: KernelEvents::EXCEPTION)]
+class ExceptionListener
+{
+    public function __construct(
+        private readonly Environment $twig,
+        private readonly string $kernelEnvironment,
+    ) {
+    }
+
+    public function __invoke(ExceptionEvent $event): void
+    {
+        if ('dev' === $this->kernelEnvironment) {
+            return;
+        }
+
+        $exception = $event->getThrowable();
+        $statusCode = $exception instanceof HttpExceptionInterface ? $exception->getStatusCode() : 500;
+
+        if (404 === $statusCode) {
+            $template = 'error/404.html.twig';
+        } else {
+            $template = 'error/500.html.twig';
+        }
+
+        $response = new Response(
+            $this->twig->render($template, ['status_code' => $statusCode]),
+            $statusCode,
+        );
+
+        if ($exception instanceof HttpExceptionInterface) {
+            $response->headers->add($exception->getHeaders());
+        }
+
+        $event->setResponse($response);
+    }
+}

templates/error/404.html.twig

@@ -0,0 +1,24 @@
+{% extends 'base.html.twig' %}
+
+{% block title %}Page introuvable - E-Ticket{% endblock %}
+
+{% block body %}
+<div class="bg-[#fbfbfb] overflow-x-hidden italic font-sans">
+    <section class="relative flex items-center justify-center px-4 pt-20 pb-16 min-h-[60vh]">
+        <div class="absolute inset-0 opacity-[0.03] pointer-events-none select-none overflow-hidden">
+            <span class="text-[20rem] font-black uppercase leading-none block -rotate-12 translate-y-10">404</span>
+        </div>
+
+        <div class="max-w-2xl mx-auto relative z-10 text-center">
+            <div class="border-4 border-gray-900 bg-white shadow-[6px_6px_0px_rgba(0,0,0,1)] p-12">
+                <div class="text-8xl font-black uppercase tracking-tighter mb-4">404</div>
+                <h1 class="text-3xl font-black uppercase tracking-tighter italic mb-4">Page introuvable</h1>
+                <p class="font-bold text-gray-500 italic mb-8">La page que vous cherchez n'existe pas ou a ete deplacee.</p>
+                <a href="/" style="padding:0.75rem 2rem;border:3px solid #111827;box-shadow:4px 4px 0 rgba(0,0,0,1);background:#fabf04;display:inline-block;" class="font-black uppercase text-sm tracking-widest hover:bg-indigo-600 hover:text-white transition-all">
+                    Retour a l'accueil
+                </a>
+            </div>
+        </div>
+    </section>
+</div>
+{% endblock %}

templates/error/500.html.twig

@@ -0,0 +1,24 @@
+{% extends 'base.html.twig' %}
+
+{% block title %}Erreur serveur - E-Ticket{% endblock %}
+
+{% block body %}
+<div class="bg-[#fbfbfb] overflow-x-hidden italic font-sans">
+    <section class="relative flex items-center justify-center px-4 pt-20 pb-16 min-h-[60vh]">
+        <div class="absolute inset-0 opacity-[0.03] pointer-events-none select-none overflow-hidden">
+            <span class="text-[20rem] font-black uppercase leading-none block -rotate-12 translate-y-10">500</span>
+        </div>
+
+        <div class="max-w-2xl mx-auto relative z-10 text-center">
+            <div class="border-4 border-gray-900 bg-white shadow-[6px_6px_0px_rgba(0,0,0,1)] p-12">
+                <div class="text-8xl font-black uppercase tracking-tighter mb-4">{{ status_code }}</div>
+                <h1 class="text-3xl font-black uppercase tracking-tighter italic mb-4">Erreur serveur</h1>
+                <p class="font-bold text-gray-500 italic mb-8">Une erreur inattendue s'est produite. Nos equipes ont ete notifiees.</p>
+                <a href="/" style="padding:0.75rem 2rem;border:3px solid #111827;box-shadow:4px 4px 0 rgba(0,0,0,1);background:#fabf04;display:inline-block;" class="font-black uppercase text-sm tracking-widest hover:bg-indigo-600 hover:text-white transition-all">
+                    Retour a l'accueil
+                </a>
+            </div>
+        </div>
+    </section>
+</div>
+{% endblock %}

tests/EventListener/ExceptionListenerTest.php

@@ -0,0 +1,86 @@
+<?php
+
+namespace App\Tests\EventListener;
+
+use App\EventListener\ExceptionListener;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+use Twig\Environment;
+
+class ExceptionListenerTest extends TestCase
+{
+    public function testDoesNothingInDevEnvironment(): void
+    {
+        $twig = $this->createMock(Environment::class);
+        $twig->expects(self::never())->method('render');
+
+        $listener = new ExceptionListener($twig, 'dev');
+        $event = $this->createEvent(new \RuntimeException('test'));
+
+        $listener($event);
+
+        self::assertNull($event->getResponse());
+    }
+
+    public function testRenders404Template(): void
+    {
+        $twig = $this->createMock(Environment::class);
+        $twig->expects(self::once())
+            ->method('render')
+            ->with('error/404.html.twig', ['status_code' => 404])
+            ->willReturn('<h1>404</h1>');
+
+        $listener = new ExceptionListener($twig, 'prod');
+        $event = $this->createEvent(new NotFoundHttpException('Not found'));
+
+        $listener($event);
+
+        self::assertNotNull($event->getResponse());
+        self::assertSame(404, $event->getResponse()->getStatusCode());
+        self::assertSame('<h1>404</h1>', $event->getResponse()->getContent());
+    }
+
+    public function testRenders500TemplateForGenericException(): void
+    {
+        $twig = $this->createMock(Environment::class);
+        $twig->expects(self::once())
+            ->method('render')
+            ->with('error/500.html.twig', ['status_code' => 500])
+            ->willReturn('<h1>500</h1>');
+
+        $listener = new ExceptionListener($twig, 'prod');
+        $event = $this->createEvent(new \RuntimeException('Server error'));
+
+        $listener($event);
+
+        self::assertNotNull($event->getResponse());
+        self::assertSame(500, $event->getResponse()->getStatusCode());
+    }
+
+    public function testRenders500TemplateForOtherHttpCodes(): void
+    {
+        $twig = $this->createMock(Environment::class);
+        $twig->expects(self::once())
+            ->method('render')
+            ->with('error/500.html.twig', ['status_code' => 403])
+            ->willReturn('<h1>403</h1>');
+
+        $listener = new ExceptionListener($twig, 'prod');
+        $event = $this->createEvent(new \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException('Forbidden'));
+
+        $listener($event);
+
+        self::assertNotNull($event->getResponse());
+        self::assertSame(403, $event->getResponse()->getStatusCode());
+    }
+
+    private function createEvent(\Throwable $exception): ExceptionEvent
+    {
+        $kernel = $this->createMock(HttpKernelInterface::class);
+
+        return new ExceptionEvent($kernel, new Request(), HttpKernelInterface::MAIN_REQUEST, $exception);
+    }
+}