Gulp v4 Build

gulpfile.js

const gulp = require('gulp'),
  less = require('gulp-less'),
  babel = require("gulp-babel"),
  shell = require('gulp-shell'),
  mocha = require('gulp-mocha'),
  rename = require('gulp-rename'),
  bro = require('gulp-bro'),
  del = require('del'),
  { series, dest, src } = require('gulp');

require('dotenv').config();

const config = {
  watch: {
    src: './src/*.js'
  },
  test: {
    path: {
      specs: './test/specs/*-spec.js'
    },
    mocha: {
      reporter: 'spec'
    }
  }
};

function precompile(cb) {
  src('./src/client/less/*.less')
    .pipe(less({
      compress: true
    }))
    .pipe(gulp.dest('./build/client/css'));
  cb();
}

function clean() {
  return del(['build', 'distribute']);
}

function transpile() {
  return src(['./src/**/*.js', '!./src/client/less/*.js'])
    .pipe(babel())
    .pipe(gulp.dest("build"));
}

function copyBuild(){
  return src(['src/shared/**/*.json']).pipe(dest('build/shared'));
}

function copyExt() {
  return src(['ext/**/*']).pipe(dest('dist/client/lib'));
}

function copyData() {
  return src(['src/shared/**']).pipe(dest('dist/shared'));
}

function copyAssets() {
  return src(['src/client/assets/**']).pipe(dest('dist/client/lib/assets'));
}

function copyStyles() {
  return src(['./build/client/css/*.css']).pipe(dest('dist/client/lib/css'));
}

function copyFeed() {
  return src(['feed.xml']).pipe(dest('dist/client'));
}

function copyBuildAndDist() {
  return src(['build/server.js', 'build/api.js', 'build/shared', 'src/**/index.html', 'package.json']).pipe(dest('dist'));
}

function link(cb) {
  shell.task(['ln -s ' + process.cwd() + '/node_modules ' + process.cwd() + '/dist/node_modules']);
  cb();
}

function tar(cb){
  shell.task(['tar -C dist -cf we-do-tdd.tar ./']);
  cb();
}

function bundle() {
  return src('build/client/index.js')

    .pipe(bro({
      transform: [
        [ 'uglifyify', { global: true } ]
      ]
    }))
    .pipe(rename('app.bundle.js'))
    .pipe(dest('dist/client/scripts/'));
}

function createDist() {
  return src(['./'], { allowEmpty: true }).pipe(dest('dist/client/scripts'));
}

function specFontEnd() {
  process.env.PORT = 8001;

  return src(['build/test/spec/frontend/**/*-spec.js'], {read: false})
    .pipe(mocha({
      reporter: config.test.mocha.reporter,
      ui: 'bdd'
    }));
}

function specBackEnd() {
  process.env.PORT = 8001;
  return src(['build/test/spec/backend/**/*-spec.js'], {read: false})
    .pipe(mocha({
      reporter: config.test.mocha.reporter,
      ui: 'bdd'
    }));
}

function specAll() {
  process.env.PORT = 8001;
  return src(['build/test/spec/**/*-spec.js'], {read: false})
    .pipe(mocha({
      reporter: config.test.mocha.reporter,
      ui: 'bdd'
    }));
}

exports.build = series(clean, transpile, copyBuild);
exports.distribute = series(
  clean,
  transpile,
  copyBuild,
  createDist,
  copyBuildAndDist,
  copyExt,
  link,
  bundle,
  precompile,
  copyData,
  copyAssets,
  copyStyles,
  copyFeed,
  tar);
exports.clean = clean;
exports.precompile = precompile;
exports.transpile = transpile;
exports.copyBuild = copyBuild;
exports.copyExt = copyExt;
exports.copyData = copyData;
exports.copyAssets = copyAssets;
exports.copyStyles = copyStyles;
exports.copyFeed = copyFeed;
exports.copyBuildAndDist = copyBuildAndDist;
exports.bundle = bundle;
exports.createDist = createDist;
exports.specFontEnd = specFontEnd;
exports.specBackEnd = specBackEnd;
exports.specAll = specAll;
exports.default = link;
exports.default = tar;