public function testListServer()
 {
     $serverList = $this->compute->listServers();
     $this->assertTrue($serverList instanceof Compute\ServerList);
     if (!empty(self::$serverId)) {
         $found = false;
         foreach ($serverList as $server) {
             if ($server->getId() === self::$serverId) {
                 $found = true;
                 break;
             }
         }
         $this->assertTrue($found);
     }
 }