refactor(code): using constructor

for encapsulation and state

BREAKING CHANGE: the API has changed
from findNewRules(currentRules, pluginRules)
to getRuleFinder('path/to/eslint-config').getUnusedRules()

bin.js

@@ -4,14 +4,11 @@
 
 // Prints rules recognized by ESLint that don't appear in the given config
 // preset. It helps with upgrading the preset when new ESLint gets released.
-var binUtils = require('./bin-utils')
-var findNewRules = require('./index')
+var RuleFinder = require('./rule-finder')
+var specifiedFile = process.argv[2]
+var ruleFinder = new RuleFinder(specifiedFile);
 
-var config = binUtils.getConfig(process.argv[2])
-var currentRules = binUtils.getCurrentRules(config)
-var pluginRules = binUtils.getPluginRules(config)
-
-var newRules = findNewRules(currentRules, pluginRules)
+var newRules = ruleFinder.getNewRules()
 
 if (newRules.length) {
   console.log('New rules to add to the config: ' + newRules.join(', ') + '.') // eslint-disable-line no-console

package.json

@@ -2,7 +2,7 @@
   "name": "eslint-find-new-rules",
   "version": "0.0.0-semantically-released",
   "description": "Find built-in ESLint rules you don't have in your custom config.",
-  "main": "index.js",
+  "main": "src/rule-finder.js",
   "scripts": {
     "cover": "nyc --reporter=lcov --reporter=text ava",
     "test": "ava",
@@ -16,7 +16,7 @@
     "report-coverage": "cat ./coverage/lcov.info | node_modules/.bin/codecov"
   },
   "bin": {
-    "eslint-find-new-rules": "bin.js"
+    "eslint-find-new-rules": "src/bin.js"
   },
   "keywords": [],
   "author": "Michał Gołębiowski <[email protected]>",
@@ -78,4 +78,4 @@
     "url": "https://github.com/kentcdodds/eslint-find-new-rules/issues"
   },
   "homepage": "https://github.com/kentcdodds/eslint-find-new-rules#readme"
-}
+}

rule-finder.js

@@ -0,0 +1,98 @@
+var path = require('path')
+var fs = require('fs')
+
+var eslint = require('eslint')
+var isAbsolute = require('path-is-absolute')
+var difference = require('lodash.difference')
+
+function _getConfigFile(specifiedFile) {
+  if (specifiedFile) {
+    if (isAbsolute(specifiedFile)) {
+      return specifiedFile
+    } else {
+      return path.join(process.cwd(), specifiedFile)
+    }
+  } else {
+    // this is not being called with an arg. Use the package.json `main`
+    return require(path.join(process.cwd(), 'package.json')).main
+  }
+}
+
+function _getConfig(configFile) {
+  var cliEngine = new eslint.CLIEngine({
+    // ignore any config applicable depending on the location on the filesystem
+    useEslintrc: false,
+    // point to the particular config
+    configFile: configFile, // eslint-disable-line object-shorthand
+  })
+  return cliEngine.getConfigForFile()
+}
+
+function _getCurrentRules() {
+  var config = this.getConfig()
+  return Object.keys(config.rules)
+}
+
+function _getPluginRules() {
+  var config = this.getConfig()
+  var pluginRules = []
+  var plugins = config.plugins
+  if (plugins) {
+    plugins.forEach(function getPluginRule(plugin) {
+      var pluginConfig = require('eslint-plugin-' + plugin)
+      var rules = pluginConfig.rules
+      pluginRules = pluginRules.concat(
+        Object.keys(rules).map(function normalizePluginRule(rule) {
+          return plugin + '/' + rule
+        })
+      )
+    })
+  }
+  return pluginRules
+}
+
+function _getAllRules() {
+  var pluginRules = this.getPluginRules()
+  var allRules = fs
+    .readdirSync('./node_modules/eslint/lib/rules')
+    .map(function removeJsFromFilename(filename) {
+      return filename.replace(/\.js$/, '')
+    })
+
+  allRules = allRules.concat(pluginRules)
+
+  return allRules
+}
+
+var RuleFinder = function(specifiedFile) {
+  var configFile = _getConfigFile(specifiedFile)
+  var config = _getConfig(configFile)
+  var currentRules
+  var pluginRules
+  var allRules
+
+  this.getConfig = function() {
+    return config
+  }
+
+  currentRules = _getCurrentRules.call(this)
+  this.getCurrentRules = function() {
+    return currentRules
+  }
+
+  pluginRules = _getPluginRules.call(this)
+  this.getPluginRules = function() {
+    return pluginRules
+  }
+
+  allRules = _getAllRules.call(this)
+  this.getAllRules = function() {
+    return allRules
+  }
+}
+
+RuleFinder.prototype.getNewRules = function() {
+  return difference(this.getAllRules(), this.getCurrentRules())
+}
+
+module.exports = RuleFinder