How the hell do you unit test this???

FAFSServer.php

<?php
/**
 * Gary Hockin
 * 23/04/2013
 */

namespace FAFSServer\Service;

class FAFSServer
{
    /**
     * @var array
     */
    protected $config;

    /**
     * @param array $config
     */
    public function __construct(array $config)
    {
        $this->config = $config;
    }

    public function start()
    {
        // get config values (or use some sane defaults)
        $ip = isset($this->config['ip']) ? $this->config['ip'] : '127.0.0.1';
        $port = isset($this->config['port']) ? $this->config['port'] : '6610';
        $length = isset($this->config['maxLength']) ? $this->config['maxLength'] : 1024;

        // Create socket server
        $socket = stream_socket_server("udp://$ip:$port", $errorNo, $errorMessage, STREAM_SERVER_BIND);
        if ($errorNo || $errorMessage || get_resource_type($socket) !== 'stream') {
            throw new \Exception("Error creating server: $errorMessage", $errorNo);
        }

        // Loop through data as it's received
        while ($data = stream_socket_recvfrom($socket, $length, null, $receivedFrom)) {
            echo "$data \r\n";
        }
    }
}