Kick off the SDK based on Symfony's MCP SDK

tests/Message/ResponseTest.php

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+<?php
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Mcp\Tests\Message;
+
+use Mcp\Message\Response;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\Small;
+use PHPUnit\Framework\TestCase;
+
+#[Small]
+#[CoversClass(Response::class)]
+final class ResponseTest extends TestCase
+{
+    public function testWithIntegerId(): void
+    {
+        $response = new Response(1, ['foo' => 'bar']);
+        $expected = [
+            'jsonrpc' => '2.0',
+            'id' => 1,
+            'result' => ['foo' => 'bar'],
+        ];
+
+        $this->assertSame($expected, $response->jsonSerialize());
+    }
+
+    public function testWithStringId(): void
+    {
+        $response = new Response('abc', ['foo' => 'bar']);
+        $expected = [
+            'jsonrpc' => '2.0',
+            'id' => 'abc',
+            'result' => ['foo' => 'bar'],
+        ];
+
+        $this->assertSame($expected, $response->jsonSerialize());
+    }
+}