add a test in ServerResponseTest and the code-style command

composer.json

@@ -3,6 +3,9 @@
     "description": "A guzzle/psr-7 wrapper to add additional functionality like sending responses and managing cookies",
     "type": "library",
     "license": "MIT",
+    "scripts": {
+        "code-style": "phpcs --standard=PSR2 src && phpcs --standard=PSR2 --ignore=example tests"
+    },
     "require": {
         "guzzlehttp/psr7": "^1.4.2"
     },

tests/ClientResponseTest.php

@@ -239,7 +239,7 @@ class ClientResponseTest extends TestCase
     {
         $r1 = new Response(200, ['OWS' => " \t \tFoo\t \t "]);
         $r2 = (new Response())->withHeader('OWS', " \t \tFoo\t \t ");
-        $r3 = (new Response())->withAddedHeader('OWS', " \t \tFoo\t \t ");;
+        $r3 = (new Response())->withAddedHeader('OWS', " \t \tFoo\t \t ");
 
         foreach ([$r1, $r2, $r3] as $r) {
             $this->assertSame(['OWS' => ['Foo']], $r->getHeaders());

tests/ServerResponseTest.php

@@ -3,8 +3,18 @@
 namespace Tal\Test;
 
 use PHPUnit\Framework\TestCase;
+use Tal\ServerResponse;
 
 class ServerResponseTest extends TestCase
 {
+    public function testSetCookieAddsHeader()
+    {
+        $response = new ServerResponse();
 
+        $response->setCookie('foo', 'bar');
+
+        self::assertEquals([
+            'Set-Cookie' => ['foo=bar']
+        ], $response->getHeaders());
+    }
 }