Uncaught Error: Class "MyApp\Chat" not found

[cancavid]

root
├── bin
│ └── server.php
├── src
│ └── Chat.php
├── composer.json
├── composer.lock
└── vendor

composer.json is

{
    "autoload": {
        "psr-4": {
            "MyApp\\": "src"
        }
    },
    "require": {
        "cboden/ratchet": "^0.4.4"
    }
}

server.php

use Ratchet\Server\IoServer;
use Ratchet\Http\HttpServer;
use Ratchet\WebSocket\WsServer;
use MyApp\Chat;

require dirname(__DIR__) . '/vendor/autoload.php';

$server = IoServer::factory(
  new HttpServer(
    new WsServer(
      new Chat()
    )
  ),
  8080
);

$server->run();

chat.php

namespace MyApp;
use Ratchet\MessageComponentInterface;
use Ratchet\ConnectionInterface;

require_once dirname(__DIR__) . '/vendor/autoload.php';

class Chat implements MessageComponentInterface {
}

I used composer update AND composer dump-autoload

but problem is continue