[WIP] Migrate from Gulp to Fly (#965)

* install fly & plugins

* start flyfile conversion

* install node-notifier directly

* send task notifications

* upgrade to fly@2.0.1

* fix watch rebuilds

* compile in parallel

* remove gulp-related deps

* enable start|stop-chromedriver

* run build before watching

* extract webpack config

* fix webpack build

* use serial chain within 'build' -- faster

* update to fly-watch@1.1.0

* generate new yarn.lock after rebase

* rename tasks; use fly-esnext (async/await)

* bump fly deps (node4 supp)

* remove destructured assignment

* import latest package.json changes

flyfile.js

@@ -0,0 +1,109 @@
+const webpack = require('webpack')
+const notifier = require('node-notifier')
+const childProcess = require('child_process')
+const webpackConfig = require('./webpack.config')
+const isWindows = /^win/.test(process.platform)
+
+export async function compile(fly) {
+  await fly.parallel(['bin', 'server', 'lib', 'client'])
+  await fly.start('unrestrict')
+}
+
+export async function bin(fly, opts) {
+  await fly.source(opts.src || 'bin/*').babel().target('dist/bin')
+  notify('Compiled binaries')
+}
+
+export async function lib(fly, opts) {
+  await fly.source(opts.src || 'lib/**/*.js').babel().target('dist/lib')
+  notify('Compiled lib files')
+}
+
+export async function server(fly, opts) {
+  await fly.source(opts.src || 'server/**/*.js').babel().target('dist/server')
+  notify('Compiled server files')
+}
+
+export async function client(fly, opts) {
+  await fly.source(opts.src || 'client/**/*.js').babel().target('dist/client')
+  notify('Compiled client files')
+}
+
+export async function unrestrict(fly) {
+  await fly.source('dist/lib/eval-script.js').babel({
+    babelrc: false,
+    plugins: ['babel-plugin-transform-remove-strict-mode']
+  }).target('dist/lib')
+  notify('Completed removing strict mode for eval script')
+}
+
+export async function copy(fly) {
+  await fly.source('pages/**/*.js').target('dist/pages')
+}
+
+export async function build(fly) {
+  await fly.serial(['copy', 'compile', 'prefetcher'])
+}
+
+const compiler = webpack(webpackConfig)
+export async function prefetcher(fly) {
+  compiler.run((err, stats) => {
+    if (err) throw err
+    notify('Built release prefetcher')
+  })
+}
+
+export async function bench(fly) {
+  await fly.parallel(['compile', 'copy'])
+  // copy bench fixtures
+  await fly.source('bench/fixtures/**/*').target('dist/bench/fixtures')
+  // compile bench
+  await fly.source('bench/*.js').babel().target('dist/bench')
+  notify('Compiled bench files')
+  // yield fly.source('dist/bench/*.js').benchmark({
+    // benchmark.reporters.etalon('RegExp#test')
+  // })
+}
+
+export default async function (fly) {
+  await fly.start('build')
+  await fly.watch('bin/*', 'bin')
+  await fly.watch('pages/**/*.js', 'copy')
+  await fly.watch('server/**/*.js', 'server')
+  await fly.watch('client/**/*.js', ['client', 'prefetcher'])
+  await fly.watch('lib/**/*.js', ['lib', 'prefetcher'])
+}
+
+export async function release(fly) {
+  await fly.clear('dist').start('build')
+}
+
+// We run following task inside a NPM script chain and it runs chromedriver
+// inside a child process tree.
+// Even though we kill this task's process, chromedriver exists throughout
+// the lifetime of the original npm script.
+
+export async function pretest(fly) {
+  const processName =  isWindows ? 'chromedriver.cmd' : 'chromedriver'
+  const chromedriver = childProcess.spawn(processName, { stdio: 'inherit' })
+  // We need to do this, otherwise this task's process will keep waiting.
+  setTimeout(() => process.exit(0), 2000)
+}
+
+export async function posttest(fly) {
+  try {
+    const cmd = isWindows ? 'taskkill /im chromedriver* /t /f' : 'pkill chromedriver'
+    childProcess.execSync(cmd, { stdio: 'ignore' })
+  } catch(err) {
+    // Do nothing
+  }
+}
+
+// notification helper
+function notify(msg) {
+  return notifier.notify({
+    title: '▲ Next',
+    message: msg,
+    icon: false
+  })
+}

package.json

@@ -23,11 +23,11 @@
     "next": "./dist/bin/next"
   },
   "scripts": {
-    "build": "gulp",
-    "release": "gulp release",
-    "pretestonly": "gulp start-chromedriver",
+    "build": "fly",
+    "release": "fly release",
+    "pretestonly": "fly pretest",
     "testonly": "cross-env NODE_PATH=test/lib jest \\.test.js",
-    "posttestonly": "gulp stop-chromedriver",
+    "posttestonly": "fly posttest",
     "pretest": "npm run lint && cross-env NODE_ENV=test npm run release",
     "test": "npm run testonly -- --coverage --forceExit",
     "coveralls": "nyc --instrument=false --source-map=false report --temp-directory=./coverage --reporter=text-lcov | coveralls",
@@ -95,21 +95,20 @@
     "chromedriver": "^2.26.1",
     "coveralls": "2.11.16",
     "cross-env": "^3.1.4",
-    "gulp": "3.9.1",
-    "gulp-babel": "6.1.2",
-    "gulp-benchmark": "1.1.1",
-    "gulp-cached": "1.1.1",
-    "gulp-notify": "3.0.0",
+    "fly": "^2.0.3",
+    "fly-babel": "^2.1.1",
+    "fly-clear": "^1.0.1",
+    "fly-esnext": "^2.0.0",
+    "fly-watch": "^1.1.1",
     "husky": "0.13.1",
     "jest-cli": "^18.0.0",
     "node-fetch": "^1.6.3",
+    "node-notifier": "^5.0.2",
     "nyc": "^10.0.0",
     "react": "15.4.2",
     "react-dom": "15.4.2",
-    "run-sequence": "1.2.2",
     "standard": "8.6.0",
-    "wd": "^1.1.3",
-    "webpack-stream": "3.2.0"
+    "wd": "^1.1.3"
   },
   "peerDependencies": {
     "react": "^15.4.2",

webpack.config.js

@@ -0,0 +1,35 @@
+const resolve = require('path').resolve
+const webpack = require('webpack')
+
+module.exports = {
+  entry: './client/next-prefetcher.js',
+  output: {
+    filename: 'next-prefetcher-bundle.js',
+    path: resolve(__dirname, 'dist/client')
+  },
+  plugins: [
+    new webpack.DefinePlugin({
+      'process.env': {
+        NODE_ENV: JSON.stringify('production')
+      }
+    })
+  ],
+  module: {
+    rules: [{
+      test: /\.js$/,
+      exclude: /node_modules/,
+      loader: 'babel-loader',
+      options: {
+        babelrc: false,
+        presets: [
+          ['env', {
+            targets: {
+              // All browsers which supports service workers
+              browsers: ['chrome 49', 'firefox 49', 'opera 41']
+            }
+          }]
+        ]
+      }
+    }]
+  }
+}