<?php class Swift_Bug118Test extends \PHPUnit\Framework\TestCase { private $message; protected function setUp() { $this->message = new Swift_Message(); } public function testCallingGenerateIdChangesTheMessageId() { $currentId = $this->message->getId(); $this->message->generateId(); $newId = $this->message->getId(); $this->assertNotEquals($currentId, $newId); } }