Improve option name validation message

- Also bump eslint to allow es6

.eslintrc

@@ -1,5 +1,8 @@
 {
   "extends": "eslint:recommended",
+  "parserOptions": {
+    "ecmaVersion": 6
+  },
   "env": {
     "node": true,
     "mocha": true

lib/index.js

@@ -210,11 +210,15 @@ Base.prototype.option = function option(name, config) {
   });
 
   // Check whether boolean option is invalid (starts with no-)
-  if (config.type === Boolean && name.match(/^no-.+/)) {
-    return this.emit('error', new Error('Option name ' + chalk.bold(name) +
-                                        ' cannot start with no-\nTo allow user to pass `--no-' +
-                                        name + '` use `this.option({' +
-                                        name + '}, {type: Boolean})` instead.'));
+  var boolOptionRegex = /^no-/;
+  if (config.type === Boolean && name.match(boolOptionRegex)) {
+    let simpleName = name.replace(boolOptionRegex, '');
+    return this.emit('error', new Error([
+      `Option name ${chalk.yellow(name)} cannot start with ${chalk.red('no-')}\n`,
+      `Option name prefixed by ${chalk.yellow('--no')} are parsed as implicit`,
+      ` boolean. To use ${chalk.yellow('--' + name)} as an option, use\n`,
+      chalk.cyan(`  this.option('${simpleName}', {type: Boolean})`)
+    ].join('')));
   }
 
   if (this._options[name] == null) {

package.json

@@ -66,10 +66,10 @@
   "devDependencies": {
     "gulp": "^3.6.0",
     "gulp-coveralls": "^0.1.0",
-    "gulp-eslint": "^2.0.0",
+    "gulp-eslint": "^3.0.1",
     "gulp-exclude-gitignore": "^1.0.0",
     "gulp-istanbul": "^1.0.0",
-    "gulp-mocha": "^2.0.0",
+    "gulp-mocha": "^3.0.1",
     "gulp-nsp": "^2.1.0",
     "gulp-plumber": "^1.0.0",
     "inquirer": "^1.0.2",

test/base.js

@@ -710,7 +710,7 @@ describe('Base', function () {
       var addWrongOp = function() {
         generator.option('no-op');
       };
-      assert.throws(addWrongOp, Error);
+      assert.throws(addWrongOp, /this\.option\('op', \{type: Boolean\}\)/);
     });
 
   });