chore(build): Reworks babel build

* Add module export in project root
* Remove npmignore in favor of files array in package.json
* Adds minimal Gulp v4 build
  - clean
  - lint ( ESLint ./src )
  - build ( Babel transpile to ./lib )
  - watch ( Standard watch & rebuild )
  - default ( Cleans, lints & builds )

.gitignore

@@ -1,3 +1,3 @@
 node_modules
 coverage
-dist
+lib

gulpfile.js

@@ -0,0 +1,71 @@
+const gulp = require('gulp')
+const del = require('del')
+const util = require('gulp-util')
+const eslint = require('gulp-eslint')
+const babel = require('gulp-babel')
+
+gulp.task('clean', function(done) {
+  del([
+    'lib/**/*',
+  ])
+  done()
+})
+
+/**
+ * Lints all the JavaScript in the project.
+ * Ignores transpiled code & node_modules.
+ */
+gulp.task('lint', function(done) {
+  gulp.src(['**/*.js', '!node_modules/**', '!lib/**'])
+    .pipe(eslint())
+    .pipe(eslint.format())
+    .pipe(eslint.failAfterError())
+  done()
+})
+
+/**
+ * Transpiles with Babel based on defined presets.
+ */
+gulp.task('build', function(done) {
+  gulp.src('src/**/*.js')
+    .pipe(babel({
+      presets: ['es2015', 'stage-2']
+    }))
+    .pipe(gulp.dest('lib'))
+  done()
+})
+
+/**
+ * Watches for changes in the src directory.
+ * "on change" transpiles incrementally.
+ * "on unlink" removes the transpiled version of the deleted file.
+ */
+gulp.task('watch', function() {
+  gulp.watch('src/**/*.js')
+    .on('change', function(path) {
+      gulp.src(path)
+        .pipe(babel({
+          presets: ['es2015', 'stage-2']
+        }))
+        .pipe(gulp.dest('lib'))
+      util.log(`File "${path}" rebuilt`)
+    })
+    .on('unlink', function(path) {
+      util.log(`File "${path}" removed`)
+      let filePathFromSrc = path.relative(path.resolve('src'))
+      let destFilePath = path.resolve('build', filePathFromSrc)
+
+      del.sync(destFilePath)
+    })
+})
+
+/**
+ * Entrypoint for running watch.
+ */
+gulp.task('build.watch', gulp.series('build', 'watch', function(done) {
+  done()
+}))
+
+gulp.task('default', gulp.series('clean', 'lint', 'build', function(done) {
+  done()
+}))

index.js

@@ -0,0 +1,5 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+module.exports = require('./lib/karma-webpack')

package.json

@@ -5,19 +5,24 @@
   "description": "Use webpack with karma",
   "license": "MIT",
   "homepage": "http://github.com/webpack/karma-webpack",
-  "main": "dist/karma-webpack.js",
   "scripts": {
-    "lint": "eslint test src",
+    "gulp": "gulp",
+    "lint": "gulp lint",
+    "clean": "gulp clean",
     "pretest": "npm run lint",
     "test": "npm run test.unit",
     "test.unit": "mocha --compilers js:babel-register --full-trace --check-leaks test/unit",
     "test.integration": "npm run build && karma start --single-run",
     "travis": "npm run test.unit && npm run test.integration",
     "generate.changelog": "node scripts/release/generate-changelog.js",
-    "publish.version": "npm run build:dist && sh scripts/release/npm-publish.sh",
-    "build:dev": "webpack",
-    "build:dist": "cross-env NODE_ENV=production webpack"
+    "publish.version": "npm run build && sh scripts/release/npm-publish.sh",
+    "build:watch": "gulp build.watch",
+    "build": "gulp build"
   },
+  "files": [
+    "lib",
+    "index.js"
+  ],
   "repository": {
     "type": "git",
     "url": "https://github.com/webpack/karma-webpack.git"
@@ -47,8 +52,14 @@
     "conventional-changelog": "^1.1.0",
     "cross-env": "^2.0.0",
     "cz-conventional-changelog": "^1.1.6",
+    "del": "^2.2.1",
     "eslint": "^3.1.1",
     "eslint-plugin-babel": "^3.3.0",
+    "gulp": "github:gulpjs/gulp#4.0",
+    "gulp-babel": "^6.1.2",
+    "gulp-eslint": "^3.0.1",
+    "gulp-util": "^3.0.7",
+    "gulp-watch": "^4.3.9",
     "istanbul": "^0.4.4",
     "json-loader": "^0.5.4",
     "karma": "^1.x",

scripts/release/README.md

@@ -13,4 +13,4 @@
 
 *The NPM Portion*
 * `npm login` to the user with rights to publish to NPM
-* `npm run publish.version` which executes a `dist` build and publishes using the tag created above.
+* `npm run publish.version` which executes the build and publishes using the tag created above.