game_test.js

var expect = require("chai").expect

var gameOrig = "../game"
var gameGood = "../game.good"

var capturingConsole = function(action) {
  var log = console.log
  var logs = []
  global.console.log = function(msg) {
    logs.push(msg)
  }
  var result = action()
  global.console.log = log
  return logs
}

var withRandom = function(values, action) {
  var random = Math.random
  var idx = 0
  global.Math.random = function() {
    if (idx >= values.length) { idx = 0 }
    var result = values[idx]
    idx += 1
    return result
  }
  var result = action()
  global.Math.random = random
  return result
}

var origLogs, goodLogs
var assert = require("assert")
var fs = require("fs")

var randomArray = function(n) {
  var vals = []
  for (var i = 0; i < n; i++) {
    vals.push(Math.random())
  }
  return vals
}

var randomness = randomArray(100)

withRandom(randomness, function() {
  origLogs = capturingConsole(function() {
    require(gameOrig)
  })
})

withRandom(randomness, function() {
  goodLogs = capturingConsole(function() {
    require(gameGood)
  })
})

expect(origLogs).to.be.deep.equal(goodLogs)