gulpfile.js

var gulp = require('gulp');
var eslint = require('gulp-eslint');
var excludeGitignore = require('gulp-exclude-gitignore');
var mocha = require('gulp-mocha');
var istanbul = require('gulp-istanbul');
var nsp = require('gulp-nsp');
var plumber = require('gulp-plumber');
var babel = require('gulp-babel');
var del = require('del');
var isparta = require('isparta');

// Initialize the babel transpiler so ES2015 files gets compiled
// when they're loaded
require('babel-core/register');

gulp.task('static', function () {
    return gulp.src('**/*.js')
        .pipe(excludeGitignore())
        .pipe(eslint())
        .pipe(eslint.format())
        .pipe(eslint.failAfterError());
});

gulp.task('nsp', function (cb) {
    nsp('package.json', cb);
});

gulp.task('pre-test', function () {
    return gulp.src('lib/**/*.js')
        .pipe(istanbul({
            includeUntested: true
            , instrumenter: isparta.Instrumenter
        }))
        .pipe(istanbul.hookRequire());
});

gulp.task('test', ['pre-test'], function (cb) {
    var mochaErr;

    gulp.src('test/**/*.js')
        .pipe(plumber())
        .pipe(mocha({reporter: 'spec'}))
        .on('error', function (err) {
            mochaErr = err;
        })
        .pipe(istanbul.writeReports())
        .on('end', function () {
            cb(mochaErr);
        });
});

gulp.task('babel', ['clean'], function () {
    return gulp.src('lib/**/*.js')
        .pipe(babel({
            //plugins: ['transform-regenerator',
            //  'transform-es2015-unicode-regex',
            //  'transform-es2015-typeof-symbol',
            //  'transform-es2015-template-literals',
            //  'transform-es2015-sticky-regex',
            //  'transform-es2015-spread',
            //  'transform-es2015-shorthand-properties',
            //  'transform-es2015-parameters',
            //  'transform-es2015-object-super',
            //  'transform-es2015-modules-commonjs',
            //  'transform-es2015-literals',
            //  'transform-es2015-function-name',
            //  'transform-es2015-for-of',
            //  'transform-es2015-destructuring',
            //  //'transform-es2015-constants',
            //  'transform-es2015-computed-properties',
            //  'transform-es2015-arrow-functions',
            //  'transform-es2015-block-scoped-functions',
            //  'transform-es2015-block-scoping',
            //  'transform-runtime']
        }))
        .pipe(gulp.dest('dist'));
});

gulp.task('clean', function () {
    return del('dist');
});

gulp.task('prepublish', ['nsp', 'babel']);
gulp.task('default', ['static', 'test']);