public function testTitle()
{
$title1 = new Title('test');
$title2 = new Title('new test');
$message = new Message(new Body('test'));
$message1 = $message->withTitle($title1);
$this->assertSame($title1, $message1->getTitle());
$message2 = $message->withTitle($title2);
$this->assertSame($title2, $message2->getTitle());
}
