How to test Socket.IO Client in Karma's watch mode?

I have a test using Socket.IO's Client library, an angular service (http://ift.tt/1Fb7jZ6), requireJS, and a local test server. When using karma's watch feature, it runs fine the first time, but fails subsequent attempts (event listeners aren't triggered, debug logging shows an 'xhr poll error'). I think what I need to do is reset Socket.io entirely after each test using socket.io. Any ideas?

the simple version of the test is (full version):

define(['services/serviceModule', 'angular-mocks'], function() {
  describe('ILC Server Services', function() {

    var socket;

    beforeEach(module('ignisLibriColloqui.services', function(Config, $socketProvider) {
      $socketProvider.setUrl(Config.ilcTestServerUrl);
      Config.ilcServerUrl = Config.ilcTestServerUrl;
      url = Config.ilcTestServerUrl;
    }));
    beforeEach(inject(function(ILCServerService, $socket) {
      ilcServerService = ILCServerService;
      socket = $socket;
    }));

    it('expects emit(\'ping\') to trigger on(\'pong\')', function(done) {
      socket.emit('ping',{})
      socket.on('pong',function(data) {
        done();
      });
    });
  });
});

and the simple server is (full version)

var httpPort = 10999;
var socketPort = 5001;

var restify = require('restify');
var socketio = require('socket.io')(socketPort);
var fs = require('fs');

var server = restify.createServer({
  name: 'ilcServer Mock'
});

var io = socketio.listen(server);

server.get(/.*/, restify.serveStatic({
  'directory': __dirname,
  'default': './app/index.html',
  'maxAge': 0
}));

io.sockets.on('connection', function(socket) {
  var socketId = socket.id;
  console.log('user connected');
  socket.on('ping', function(data) {
    console.log('ping');
    socket.emit('pong', data);
  });
  socket.on('disconnect',function() {
    console.log('disconnect');
    socket.disconnect();
  });
});

server.listen(httpPort, function() {
  console.log('restify server listening at %s', server.url, 'socket port:', socketPort);
});