makemehapi/exercises/streams/exercise.js

Self guided workshops to teach you about hapi.

var through2 = require('through2');
var hyperquest = require('hyperquest');
var bl = require('bl');
var workshopper = require('workshopper');
var exercise = require('workshopper-exercise')();
var filecheck = require('workshopper-exercise/filecheck');
var execute = require('workshopper-exercise/execute');
var comparestdout = require('workshopper-exercise/comparestdout');

// 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);

function rndport() {

    return 1024 + Math.floor(Math.random() * 64511);
}

// 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 = [this.submissionPort];
    this.solutionArgs = [this.solutionPort];

    process.nextTick(callback);
});


// 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), 2000);

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


// delayed for 2000ms to wait for servers to start so we can start
// playing with them
function query (mode) {

    var exercise = this;

    function verify (port, stream) {

        var url = 'http://localhost:' + port + '/';

        function error (err) {
            var msg = exercise.__('fail.cannot_connect', port, err.code);
            exercise.emit('fail', msg);
        }

        hyperquest.get(url)
            .on('error', error)
            .on('response', function(res) {
                if (res.statusCode == 404 && mode == 'verify') {
                    var msg = exercise.__('fail.page_not_found', url);
                    exercise.emit('fail', msg)
                    exercise.workshopper.exerciseFail(null, exercise);
                }
            })
            .pipe(bl(function (err, data) {

                if (err)
                    return stream.emit('error', err);

                stream.write(data.toString().trim());
                stream.end();
            }));
    }

    verify(this.submissionPort, this.submissionStdout);

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


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

module.exports = exercise;