my command repeat with every refresh page in node js

Im using node js with express framework and socket.io in my project.

when i load test page in browser(with this address: http://localhost:3001/test) every thing is fine and print "a user connected" in server log but when i refresh page again print that message two time and with another refresh print that message three times and with every refresh repeat that message.

whats wrong in my code ?

thanks.

test.js

var express = require('express');
var router = express.Router();

router.get('/', function(req, res, next) {

    var io = req.io;

    io.on('connection', function(socket){
        console.log('a user connected');
    });

    res.render('test', { title: 'test' });
});

module.exports = router;

app.js

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var session = require('express-session')
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

var index = require('./routes/index');
var users = require('./routes/users');
var test = require('./routes/test');

var app = express();
var server = require('http').Server(app);
var io = require('socket.io')(server);

server.listen(3001);

app.use(function(req, res, next) {
  req.io = io;
  next();
});

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'hbs');

// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', index);
app.use('/users', users);
app.use('/test', test);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;

via AmirKH