learnyounode/exercises/http_file_server/exercise.js

Learn You The Node.js For Much Win! An intro to Node.js via a set of self-guided workshops.

var fs            = require('fs')
  , path          = require('path')
  , os            = require('os')
  , through2      = require('through2')
  , hyperquest    = require('hyperquest')
  , rimraf        = require('rimraf')
  , exercise      = require('workshopper-exercise')()
  , filecheck     = require('workshopper-exercise/filecheck')
  , execute       = require('workshopper-exercise/execute')
  , comparestdout = require('workshopper-exercise/comparestdout')
  , wrappedexec   = require('workshopper-wrappedexec')
  , rndtxt        = require('boganipsum')({ paragraphs: 1, sentenceMax: 1 }) + '\n'
  , testFile      = path.join(os.tmpDir(), '_learnyounode_' + process.pid + '.txt')
  , rndport       = require('../../lib/rndport')


// the output will be long lines so make the comparison take that into account
exercise.longCompareOutput = true

// checks that the submission file actually exists
exercise = filecheck(exercise)

// execute the solution and submission in parallel with spawn()
exercise = execute(exercise)

// add a processor for both run and verify calls, added *before*
// the comparestdout processor so we can mess with the stdouts
exercise.addProcessor(function (mode, callback) {
  this.submissionStdout.pipe(process.stdout)

  // replace stdout with our own streams
  this.submissionStdout = through2()
  if (mode == 'verify')
    this.solutionStdout = through2()

  setTimeout(query.bind(this, mode), 500)

  process.nextTick(function () {
    callback(null, true)
  })
})


// compare stdout of solution and submission
exercise = comparestdout(exercise)


// wrap up the child process in a phantom wrapper that can
// mess with the global environment and inspect execution
exercise = wrappedexec(exercise)

// a module we want run just prior to the submission in the
// child process
exercise.wrapModule(require.resolve('../my_first_io/wrap'))


// set up the data file to be passed to the submission
exercise.addSetup(function (mode, callback) {
  this.submissionPort = rndport()
  this.solutionPort   = this.submissionPort + 1

  this.submissionArgs.unshift(testFile)
  this.submissionArgs.unshift(this.submissionPort)
  this.solutionArgs.unshift(testFile)
  this.solutionArgs.unshift(this.solutionPort)

  fs.writeFile(testFile, rndtxt, 'utf8', callback)
})


// cleanup for both run and verify
exercise.addCleanup(function (mode, passed, callback) {
  // mode == 'run' || 'verify'

  rimraf(testFile, callback)
})


// delayed for 500ms to wait for servers to start so we can start
// playing with them
function query (mode) {
  var exercise = this

  function connect (port, stream) {
    //TODO: introduce verification of content-type:text/plain and statusCode=200
    var url = 'http://localhost:' + port
    hyperquest.get(url)
      .on('error', function (err) {
        exercise.emit(
            'fail'
          , exercise.__('fail.connection', {address: url, message: err.message})
        )
      })
      .pipe(stream)
  }

  connect(this.submissionPort, this.submissionStdout)

  if (mode == 'verify')
    connect(this.solutionPort, this.solutionStdout)
}


// add a processor only for 'verify' calls
exercise.addVerifyProcessor(function (callback) {
  var exercise = this
    , badCalls = Object.keys(exercise.wrapData.fsCalls).filter(function (m) {
        exercise.emit('fail', exercise.__('fail.no_createReadStream', {method: 'fs.' + m + '()'}))
        return !(/createReadStream/).test(m)
      })

  callback(null, badCalls.length === 0)
})


module.exports = exercise