add requireCapitalizedConstructors rule

README.md

@@ -658,6 +658,21 @@ Example configuration:
     */
     "requireLineFeedAtFileEnd": true,
 
+    /*
+        Option: requireCapitalizedConstructors
+        Requires constructors to be capitalized (except for "this")
+
+        Valid example:
+
+        var a = new B();
+        var c = new this();
+
+        Invalid example:
+
+        var d = new e();
+    */
+    "requireCapitalizedConstructors": true,
+
     /*
         Option: safeContextKeyword
         Option to check "var that = this" expressions

lib/rules/require-capitalized-constructors.js

@@ -0,0 +1,36 @@
+var assert = require('assert');
+
+module.exports = function() {};
+
+module.exports.prototype = {
+
+    configure: function(requireCapitalizedConstructors) {
+        assert(
+            typeof requireCapitalizedConstructors === 'boolean',
+            'requireCapitalizedConstructors option requires boolean value'
+        );
+        assert(
+            requireCapitalizedConstructors === true,
+            'requireCapitalizedConstructors option requires true value or should be removed'
+        );
+    },
+
+    getOptionName: function () {
+        return 'requireCapitalizedConstructors';
+    },
+
+    check: function(file, errors) {
+        file.iterateNodesByType('NewExpression', function(node) {
+            if (node.callee.type === 'Identifier' &&
+                node.callee.name[0].toUpperCase() !== node.callee.name[0]
+            ) {
+                errors.add(
+                    'Constructor functions should be capitalized',
+                    node.callee.loc.start.line,
+                    node.callee.loc.start.column
+                );
+            }
+        });
+    }
+
+};

lib/string-checker.js

@@ -82,6 +82,8 @@ StringChecker.prototype = {
         this.registerRule(new (require('./rules/require-spaces-in-function-expression'))());
         this.registerRule(new (require('./rules/disallow-spaces-in-function-expression'))());
 
+        this.registerRule(new (require('./rules/require-capitalized-constructors'))());
+
         this.registerRule(new (require('./rules/safe-context-keyword'))());
 
         this.registerRule(new (require('./rules/require-dot-notation'))());

test/test.require-capitalizated-constructors.js

@@ -0,0 +1,28 @@
+var Checker = require('../lib/checker');
+var assert = require('assert');
+
+describe('rules/require-capitalized-constructors', function() {
+    var checker;
+
+    beforeEach(function() {
+        checker = new Checker();
+        checker.registerDefaultRules();
+        checker.configure({ requireCapitalizedConstructors: true });
+    });
+
+    it('should report uncapitalized construction', function() {
+        assert(checker.checkString('var x = new y();').getErrorCount() === 1);
+    });
+
+    it('should not report capitalized construction', function() {
+        assert(checker.checkString('var x = new Y();').isEmpty());
+    });
+
+    it('should not report member expression construction', function() {
+        assert(checker.checkString('var x = new ns.y();').isEmpty());
+    });
+
+    it('should not report construction with "this" keyword', function() {
+        assert(checker.checkString('var x = new this();').isEmpty());
+    });
+});