Adding new rule for no-global-jquery and tests

Author: scalvert

config/recommended.js

@@ -16,6 +16,7 @@ module.exports = {
     'ember-best-practices/no-observers': 2,
     'ember-best-practices/require-dependent-keys': 2,
     'ember-best-practices/no-lifecycle-events': 2,
-    'ember-best-practices/no-attrs-snapshot': 2
+    'ember-best-practices/no-attrs-snapshot': 2,
+    'ember-best-practices/no-global-jquery': 2
   }
 };

guides/rules/no-global-jquery.md

@@ -0,0 +1,7 @@
+# No Global jQuery
+
+**TL;DR** Do not use global `$`. Use `Ember.$` instead.
+
+In general, we want application code to reference the version of jQuery that's been directly pinned
+to the version of Ember used. This helps avoid version conflicts, and ensures that code inside modules
+isn't reliant on global variables.

lib/rules/no-global-jquery.js

@@ -0,0 +1,36 @@
+/**
+ * @fileOverview Disallow the use of global `$`.
+ * @author Steve Calvert
+ */
+'use strict';
+
+/**
+ * Determines if this expression matches a global jQuery invocation.
+ * @param {ASTNode} node The identifier node.
+ * @returns {Boolean} Returns true if the expression matches, otherwise false.
+ */
+function isGlobalJquery(node) {
+  return node.callee && node.callee.name === '$';
+}
+
+const MESSAGE = 'Do not use global `$`. Use `Ember.$` instead. Please see the following guide for more infromation: https://github.com/chadhietala/ember-best-practices/blob/master/guides/rules/no-global-jquery.md';
+
+module.exports = {
+  docs: {
+    description: 'Disallow the use of global `$`',
+    category: 'Best Practices',
+    recommended: true
+  },
+  meta: {
+    message: MESSAGE
+  },
+  create(context) {
+    return {
+      CallExpression(node) {
+        if (isGlobalJquery(node)) {
+          context.report(node, MESSAGE);
+        }
+      }
+    };
+  }
+};

tests/lib/rules/no-attrs.js

@@ -3,7 +3,7 @@ const MESSAGE = rule.meta.message;
 const RuleTester = require('eslint').RuleTester;
 const ruleTester = new RuleTester();
 
-ruleTester.run('no-observers', rule, {
+ruleTester.run('no-attrs', rule, {
   valid: [
     {
       code: `

tests/lib/rules/no-global-jquery.js

@@ -0,0 +1,95 @@
+const rule = require('../../../lib/rules/no-global-jquery');
+const MESSAGE = rule.meta.message;
+const RuleTester = require('eslint').RuleTester;
+const ruleTester = new RuleTester();
+
+ruleTester.run('no-global-jquery', rule, {
+  valid: [
+    {
+      code: `
+        export default Ember.Component({
+          valid1() {
+            this.v1 = Ember.$('.v1');
+          },
+        });`,
+      parserOptions: {
+        ecmaVersion: 6,
+        sourceType: 'module'
+      }
+    },
+    {
+      code: `
+        export default Ember.Component({
+          valid2() {
+            this.v2 = this.$();
+          },
+        });`,
+      parserOptions: {
+        ecmaVersion: 6,
+        sourceType: 'module'
+      }
+    },
+    {
+      code: `
+        export default Ember.Component({
+          actions: {
+            valid3() {
+              this.v3 = Ember.$('v3');
+            }
+          }
+        });`,
+      parserOptions: {
+        ecmaVersion: 6,
+        sourceType: 'module'
+      }
+    },
+    {
+      code: `
+        export default Ember.Component({
+          actions: {
+            valid4() {
+              this.v4 = this.$('v4');
+            }
+          }
+        });`,
+      parserOptions: {
+        ecmaVersion: 6,
+        sourceType: 'module'
+      }
+    }
+  ],
+  invalid: [
+    {
+      code: `
+        export default Ember.Component({
+          init() {
+            this.el = $('.test');
+          }
+        });`,
+      parserOptions: {
+        ecmaVersion: 6,
+        sourceType: 'module'
+      },
+      errors: [{
+        message: MESSAGE
+      }]
+    },
+    {
+      code: `
+        export default Ember.Component({
+          actions: {
+            invalid1() {
+              this.inv1 = $('.invalid1');
+            }
+          }
+        });`,
+      parserOptions: {
+        ecmaVersion: 6,
+        sourceType: 'module'
+      },
+      errors: [{
+        message: MESSAGE
+      }]
+    }
+  ]
+});

tests/lib/rules/require-dependent-keys.js

@@ -3,7 +3,7 @@ const MESSAGE = rule.meta.message;
 const RuleTester = require('eslint').RuleTester;
 const ruleTester = new RuleTester();
 
-ruleTester.run('no-observers', rule, {
+ruleTester.run('require-dependent-keys', rule, {
   valid: [
     {
       code: `