Add test for EventListener

tests/EventListener/JsonResponseExceptionListener.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Tests\EventListener;
+
+use App\EventListener\JsonResponseExceptionListener;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\HttpFoundation\JsonResponse;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Symfony\Component\HttpKernel\Exception\HttpException;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+
+class JsonResponseExceptionListenerTest extends TestCase
+{
+    public function testOnKernelException()
+    {
+        $listener = new JsonResponseExceptionListener();
+
+        $kernel = $this->createMock(HttpKernelInterface::class);
+        $request = new Request();
+        $request->headers->set('Accept', 'application/json');
+        $request->headers->set('Content-Type', 'application/json');
+
+        $exception = new HttpException(400, 'Bad Request');
+        $event = new ExceptionEvent($kernel, $request, HttpKernelInterface::MAIN_REQUEST, $exception);
+
+        $listener->onKernelException($event);
+
+        $response = $event->getResponse();
+
+        $this->assertInstanceOf(JsonResponse::class, $response);
+        $this->assertEquals(400, $response->getStatusCode());
+        $this->assertJson($response->getContent());
+        $data = json_decode($response->getContent(), true);
+        $this->assertArrayHasKey('error', $data);
+        $this->assertStringContainsString('Bad Request', $data['error']);
+    }
+}