feat(fixer): add fixer for param-names (#99)

Resolves #90

Author: macklinu

README.md

@@ -88,20 +88,20 @@ or start with the recommended rule set
 
 ## Rules
 
-| recommended | rule                        | description                                                                      |
-| ----------- | --------------------------- | -------------------------------------------------------------------------------- |
-| :bangbang:  | `catch-or-return`           | Enforces the use of `catch()` on un-returned promises.                           |
-| :bangbang:  | `no-return-wrap`            | Avoid wrapping values in `Promise.resolve` or `Promise.reject` when not needed.  |
-| :bangbang:  | `param-names`               | Enforce consistent param names when creating new promises.                       |
-| :bangbang:  | `always-return`             | Return inside each `then()` to create readable and reusable Promise chains.      |
-|             | `no-native`                 | In an ES5 environment, make sure to create a `Promise` constructor before using. |
-| :warning:   | `no-nesting`                | Avoid nested `then()` or `catch()` statements                                    |
-| :warning:   | `no-promise-in-callback`    | Avoid using promises inside of callbacks                                         |
-| :warning:   | `no-callback-in-promise`    | Avoid calling `cb()` inside of a `then()` (use [nodeify][] instead)              |
-| :warning:   | `avoid-new`                 | Avoid creating `new` promises outside of utility libs (use [pify][] instead)     |
-| :warning:   | `no-return-in-finally`      | Disallow return statements in `finally()`                                        |
-| :seven:     | `prefer-await-to-then`      | Prefer `await` to `then()` for reading Promise values                            |
-| :seven:     | `prefer-await-to-callbacks` | Prefer async/await to the callback pattern                                       |
+| rule                        | description                                                                      | recommended | fixable  |
+| --------------------------- | -------------------------------------------------------------------------------- | ----------- | -------- |
+| `catch-or-return`           | Enforces the use of `catch()` on un-returned promises.                           | :bangbang:  |          |
+| `no-return-wrap`            | Avoid wrapping values in `Promise.resolve` or `Promise.reject` when not needed.  | :bangbang:  |          |
+| `param-names`               | Enforce consistent param names when creating new promises.                       | :bangbang:  | :wrench: |
+| `always-return`             | Return inside each `then()` to create readable and reusable Promise chains.      | :bangbang:  |          |
+| `no-native`                 | In an ES5 environment, make sure to create a `Promise` constructor before using. |             |          |
+| `no-nesting`                | Avoid nested `then()` or `catch()` statements                                    | :warning:   |          |
+| `no-promise-in-callback`    | Avoid using promises inside of callbacks                                         | :warning:   |          |
+| `no-callback-in-promise`    | Avoid calling `cb()` inside of a `then()` (use [nodeify][] instead)              | :warning:   |          |
+| `avoid-new`                 | Avoid creating `new` promises outside of utility libs (use [pify][] instead)     | :warning:   |          |
+| `no-return-in-finally`      | Disallow return statements in `finally()`                                        | :warning:   |          |
+| `prefer-await-to-then`      | Prefer `await` to `then()` for reading Promise values                            | :seven:     |          |
+| `prefer-await-to-callbacks` | Prefer async/await to the callback pattern                                       | :seven:     |          |
 
 **Key**
 
@@ -110,6 +110,7 @@ or start with the recommended rule set
 | :bangbang: | Reports as error in recommended configuration   |
 | :warning:  | Reports as warning in recommended configuration |
 | :seven:    | ES2017 Async Await rules                        |
+| :wrench:   | Rule is fixable with `eslint --fix`             |
 
 ### `catch-or-return`
 
@@ -215,6 +216,9 @@ way to reject the promise.
 
 Enforce standard parameter names for Promise constructors
 
+:wrench: The `--fix` option on the command line can automatically fix some of
+the problems reported by this rule.
+
 #### Valid
 
 ```js

rules/param-names.js

@@ -4,31 +4,33 @@ module.exports = {
   meta: {
     docs: {
       url: 'https://github.com/xjamundx/eslint-plugin-promise#param-names'
-    }
+    },
+    fixable: 'code'
   },
-  create: function(context) {
+  create(context) {
     return {
-      NewExpression: function(node) {
+      NewExpression(node) {
         if (node.callee.name === 'Promise' && node.arguments.length === 1) {
           const params = node.arguments[0].params
 
           if (!params || !params.length) {
             return
           }
 
-          if (params[0].name !== 'resolve') {
-            return context.report({
-              node,
-              message:
-                'Promise constructor parameters must be named resolve, reject'
-            })
-          }
-
-          if (params[1] && params[1].name !== 'reject') {
-            return context.report({
+          if (
+            params[0].name !== 'resolve' ||
+            (params[1] && params[1].name !== 'reject')
+          ) {
+            context.report({
               node,
               message:
-                'Promise constructor parameters must be named resolve, reject'
+                'Promise constructor parameters must be named resolve, reject',
+              fix(fixer) {
+                return [
+                  fixer.replaceText(params[0], 'resolve'),
+                  params[1] && fixer.replaceText(params[1], 'reject')
+                ].filter(Boolean)
+              }
             })
           }
         }

test/param-names.test.js

@@ -2,24 +2,43 @@
 
 const rule = require('../rules/param-names')
 const RuleTester = require('eslint').RuleTester
-const ruleTester = new RuleTester()
+const ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 6
+  }
+})
 
 const message = 'Promise constructor parameters must be named resolve, reject'
 
 ruleTester.run('param-names', rule, {
   valid: [
-    'new Promise(function(resolve, reject) { })',
-    'new Promise(function(resolve) { })'
+    'new Promise(function(resolve, reject) {})',
+    'new Promise(function(resolve) {})',
+    'new Promise(resolve => {})',
+    'new Promise((resolve, reject) => {})',
+    'new Promise(() => {})'
   ],
 
   invalid: [
     {
-      code: 'new Promise(function(reject, resolve) { })',
-      errors: [{ message }]
+      code: 'new Promise(function(reject, resolve) {})',
+      errors: [{ message }],
+      output: 'new Promise(function(resolve, reject) {})'
+    },
+    {
+      code: 'new Promise(function(resolve, rej) {})',
+      errors: [{ message }],
+      output: 'new Promise(function(resolve, reject) {})'
+    },
+    {
+      code: 'new Promise(yes => {})',
+      errors: [{ message }],
+      output: 'new Promise(resolve => {})'
     },
     {
-      code: 'new Promise(function(resolve, rej) { })',
-      errors: [{ message }]
+      code: 'new Promise((yes, no) => {})',
+      errors: [{ message }],
+      output: 'new Promise((resolve, reject) => {})'
     }
   ]
 })