Add test for no-primitive-constructors rule

eslint-rules/__tests__/no-primitive-constructors-test.js

@@ -0,0 +1,50 @@
+/**
+ * Copyright 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+var rule = require('../no-primitive-constructors');
+var RuleTester = require('eslint').RuleTester;
+var ruleTester = new RuleTester();
+
+ruleTester.run('eslint-rules/no-primitive-constructors', rule, {
+  valid: [
+    '!!obj',
+    "'' + obj",
+    '+string',
+  ],
+  invalid: [
+    {
+      code: 'Boolean(obj)',
+      errors: [
+        {
+          message: 'Do not use the Boolean constructor. To cast a value to a boolean, use double negation: !!value',
+        },
+      ],
+    },
+    {
+      code: 'String(obj)',
+      errors: [
+        {
+          message: 'Do not use the String constructor. To cast a value to a string, concat it with the empty string (unless it\'s a symbol, which has different semantics): \'\' + value',
+        },
+      ],
+    },
+    {
+      code: 'Number(string)',
+      errors: [
+        {
+          message: 'Do not use the Number constructor. To cast a value to a number, use the plus operator: +value',
+        },
+      ],
+    },
+  ],
+});

eslint-rules/no-primitive-constructors.js

@@ -31,7 +31,7 @@ module.exports = function(context) {
           node,
           name,
           'To cast a value to a string, concat it with the empty string ' +
-          '(unless it\'s a symbol, which have different semantics): ' +
+          '(unless it\'s a symbol, which has different semantics): ' +
           '\'\' + value'
         );
         break;