core: add eslint

.eslintrc

@@ -0,0 +1,12 @@
+{
+  "extends": "google",
+  "parserOptions": {
+    "ecmaVersion": 6,
+  },
+  "env": {
+    "node": true
+  },
+  "rules": {
+    "max-len": [2, 140, 2]
+  }
+}

gulpfile.js

@@ -22,12 +22,12 @@
  * SOFTWARE.
  */
 
-const fs = require('fs');
 const path = require('path');
 const gulp = require('gulp');
 const jasmine = require('gulp-jasmine');
 const babel = require('gulp-babel');
 const del = require('del');
+const eslint = require('gulp-eslint');
 
 gulp.task('test', ['build'], () => {
   return gulp
@@ -37,13 +37,23 @@ gulp.task('test', ['build'], () => {
 
 gulp.task('clean', () => {
   return del([
-    path.join(__dirname, 'dist')
+    path.join(__dirname, 'dist'),
   ]);
 });
 
-gulp.task('build', ['clean'], () => {
+gulp.task('build', ['clean', 'lint'], () => {
   return gulp
     .src(path.join(__dirname, 'src', 'index.js'))
     .pipe(babel())
     .pipe(gulp.dest(path.join(__dirname, 'dist')));
 });
+
+gulp.task('lint', () => {
+  const srcFiles = path.join(__dirname, 'src/**/*.js');
+  const testFiles = path.join(__dirname, 'test/**/*.js');
+  return gulp
+        .src([srcFiles, testFiles])
+        .pipe(eslint())
+        .pipe(eslint.format())
+        .pipe(eslint.failAfterError());
+});

package.json

@@ -4,6 +4,7 @@
   "description": "Rollup plugin to add license banner to the final bundle",
   "main": "dist/index.js",
   "scripts": {
+    "lint": "gulp lint",
     "clean": "gulp clean",
     "build": "gulp build",
     "test": "gulp test"
@@ -24,8 +25,11 @@
     "babel": "6.5.2",
     "babel-preset-es2015": "6.18.0",
     "del": "2.2.2",
+    "eslint": "^3.10.2",
+    "eslint-config-google": "^0.7.0",
     "gulp": "3.9.1",
     "gulp-babel": "6.1.2",
+    "gulp-eslint": "^3.0.1",
     "gulp-jasmine": "2.4.2",
     "jasmine-core": "2.5.2"
   }

src/index.js

@@ -31,7 +31,7 @@ const MagicString = require('magic-string');
 
 const EOL = '\n';
 
-module.exports = function (options) {
+module.exports = (options) => {
   return {
     transformBundle(code) {
       const file = path.resolve(options.file);