requireSpaceBeforeKeywords: added a new rule option

Ignore `function` keyword by default

Fixes #2041
Closes gh-2063

Author: gpiress

lib/rules/require-space-before-keywords.js

@@ -1,9 +1,11 @@
 /**
  * Requires space before keyword.
  *
- * Types: `Array` or `Boolean`
+ * Types: `Array`, `Boolean` or `Object`
  *
- * Values: Array of quoted keywords or `true` to require all possible keywords to have a preceding space.
+ * Values: `true` to require all possible keywords to have a preceding space (except `function`),
+ * Array of quoted keywords
+ * or an Object with the `allExcept` property set with an Array of quoted keywords.
  *
  * #### Example
  *
@@ -35,20 +37,28 @@
 var assert = require('assert');
 
 var defaultKeywords = require('../utils').spacedKeywords;
+var ignoredKeywords = ['function'];
 
 module.exports = function() {};
 
 module.exports.prototype = {
 
     configure: function(keywords) {
+        var isValidObject = (keywords === Object(keywords) && keywords.hasOwnProperty('allExcept'));
+
         assert(
-            Array.isArray(keywords) || keywords === true,
-            this.getOptionName() + ' option requires array or true value');
+            Array.isArray(keywords) || keywords === true || isValidObject,
+            this.getOptionName() + ' option requires array, object with "allExcept" property or true value');
 
-        if (keywords === true) {
-            keywords = defaultKeywords;
+        var excludedKeywords = ignoredKeywords;
+        if (isValidObject) {
+            excludedKeywords = keywords.allExcept;
         }
 
+        keywords = defaultKeywords.filter(function(keyword) {
+            return (excludedKeywords.indexOf(keyword) === -1);
+        });
+
         this._keywords = keywords;
     },
 

test/specs/rules/require-space-before-keywords.js

@@ -56,6 +56,16 @@ describe('rules/require-space-before-keywords', function() {
         expect(checker.checkString('if (true) x++;else x--;')).to.have.no.errors();
     });
 
+    it('should not report missing space on function by default', function() {
+        checker.configure({ requireSpaceBeforeKeywords: true });
+
+        expect(checker.checkString(
+            '[].forEach(function (arg) {\n' +
+                'console.log(arg);\n' +
+            '});'
+        )).to.have.no.errors();
+    });
+
     it('should report on all possible ES3 keywords if a value of true is supplied', function() {
         checker.configure({ requireSpaceBeforeKeywords: true });
 
@@ -79,4 +89,36 @@ describe('rules/require-space-before-keywords', function() {
         expect(errors).to.have.one.validation.error.from('requireSpaceBeforeKeywords');
         expect(errors.explainError(error)).to.have.string('Missing space before "catch" keyword');
     });
+
+    it('should not report missing space on excluded keyword', function() {
+        checker.configure({ requireSpaceBeforeKeywords: { allExcept: ['else'] } });
+
+        expect(checker.checkString(
+            'if (true) {\n}else { x++; }'
+        )).to.have.no.errors();
+    });
+
+    it('should report missing space in not excluded keywords', function() {
+        checker.configure({ requireSpaceBeforeKeywords: { allExcept: ['function'] } });
+
+        var errors = checker.checkString('if (true) {\n}else { x++; }');
+        var error = errors.getErrorList()[0];
+
+        expect(errors).to.have.one.validation.error.from('requireSpaceBeforeKeywords');
+        expect(errors.explainError(error)).to.have.string('Missing space before "else" keyword');
+    });
+
+    it('should report missing space on function when not specified in allExcept array', function() {
+        checker.configure({ requireSpaceBeforeKeywords: { allExcept: ['else'] } });
+
+        var errors = checker.checkString(
+            '[].forEach(function (arg) {\n' +
+                'console.log(arg);\n' +
+            '});'
+        );
+        var error = errors.getErrorList()[0];
+
+        expect(errors).to.have.one.validation.error.from('requireSpaceBeforeKeywords');
+        expect(errors.explainError(error)).to.have.string('Missing space before "function" keyword');
+    });
 });