Spark heartbeat timeout test when streaming a huge file from server to client

heartbeat.js

'use strict';

var fs = require('fs')
  , server
  , Primus = require('primus')
  , server = require('http').createServer()
  , primus = new Primus(server);

primus.on('connection', function(spark) {
  console.log(spark.id + ' connected');
  var rs = fs.createReadStream(__dirname + '/input.txt');
  rs.on('data', function(chunk) {
    spark.write(chunk.toString());
  });
  rs.on('end', function() {
    primus.end();
    console.log('done');
  });
}).on('disconnection', function(spark) {
  console.log(spark.id + ' disconnected');
});

server.listen(3000);

var client = new primus.Socket('http://localhost:3000');
client.on('open', function() {
  var ws = fs.createWriteStream(__dirname + '/output.txt');
  client.on('data', function(chunk) {
    ws.write(chunk);
  });
});