no-native rule

README.md

@@ -88,6 +88,23 @@ new Promise(function (ok, fail) { ... }) // non-standard parameter names
 
 Ensures that `new Promise()` is instantiated with the parameter names `resolve, reject` to avoid confusion with order such as `reject, resolve`. The Promise constructor uses the [RevealingConstructor pattern](https://blog.domenic.me/the-revealing-constructor-pattern/). Using the same parameter names as the language specification makes code more uniform and easier to understand.
 
+### `no-native`
+
+Ensure that `Promise` is included fresh in each file instead of relying
+ on the existence of a native promise implementation. Helpful if you want
+ to use `bluebird` or if you don't intend to use an ES6 Promise shim.
+
+
+#### Valid
+```js
+var Promise = require("blubird");
+var x = Promise.resolve("good");
+```
+
+#### Invalid
+```js
+var x = Promise.resolve("bad");
+```
 
 ## Installation
 
@@ -127,6 +144,7 @@ Then configure the rules you want to use under the rules section.
         "promise/always-return": 2,
         "promise/always-catch": 2, // deprecated
         "promise/catch-or-return": 2,
+        "promise/no-native": 0,
     }
 }
 ```

index.js

@@ -9,6 +9,7 @@ module.exports = {
     'param-names': 1,
     'always-return': 1,
     'always-catch': 1,
+    'no-native': 0,
     'catch-or-return': 1
   }
 }

rules/no-native.js

@@ -0,0 +1,45 @@
+// Borrowed from here:
+// https://github.com/colonyamerican/eslint-plugin-cah/issues/3
+
+'use strict'
+
+module.exports = function (context) {
+  var MESSAGE = '"{{name}}" is not defined.'
+
+  /**
+   * Checks for and reports reassigned constants
+   *
+   * @param {Scope} scope - an escope Scope object
+   * @returns {void}
+   * @private
+   */
+  function isDeclared (scope, ref) {
+    return scope.variables.some(function (variable) {
+      if (variable.name !== ref.identifier.name) {
+        return false
+      }
+
+      if (!variable.defs || !variable.defs.length) {
+        return false
+      }
+
+      return true
+    })
+  }
+
+  return {
+    'Program:exit': function () {
+      var scope = context.getScope()
+
+      scope.through.forEach(function (ref) {
+        if (ref.identifier.name !== 'Promise') {
+          return
+        }
+
+        if (!isDeclared(scope, ref)) {
+          context.report(ref.identifier, MESSAGE, { name: ref.identifier.name })
+        }
+      })
+    }
+  }
+}

test/no-native.js

@@ -0,0 +1,23 @@
+'use strict'
+
+var rule = require('../rules/no-native')
+var RuleTester = require('eslint').RuleTester
+
+var ruleTester = new RuleTester()
+ruleTester.run('no-native', rule, {
+  valid: [
+    'var Promise = null; function x() { return Promise.resolve("hi"); }',
+    'var Promise = window.Promise || require("bluebird"); var x = Promise.reject();'
+  ],
+
+  invalid: [
+    {
+      code: 'new Promise(function(reject, resolve) { })',
+      errors: [ { message: '"Promise" is not defined.' } ]
+    },
+    {
+      code: 'Promise.resolve()',
+      errors: [ { message: '"Promise" is not defined.' } ]
+    }
+  ]
+})