Add eslintPath option

README.md

@@ -143,6 +143,28 @@ module.exports = {
 }
 ```
 
+#### `eslintPath` (default: "eslint")
+
+Path to `eslint` instance that will be used for linting.
+
+```js
+module.exports = {
+  entry: "...",
+  module: {
+    rules: [
+      {
+        test: /\.js$/,
+        exclude: /node_modules/,
+        loader: "eslint-loader",
+        options: {
+          eslintPath: path.join(__dirname, "reusable-eslint-rules.js"),
+        }
+      },
+    ],
+  },
+  }
+```
+
 #### Errors and Warning
 
 **By default the loader will auto adjust error reporting depending

index.js

@@ -1,6 +1,5 @@
 "use strict"
 
-var eslint = require("eslint")
 var assign = require("object-assign")
 var loaderUtils = require("loader-utils")
 var objectHash = require("object-hash")
@@ -68,6 +67,7 @@ function printLinterOutput(res, config, webpack) {
 
     // if enabled, use eslint auto-fixing where possible
     if (config.fix && res.results[0].output) {
+      var eslint = require(config.eslintPath)
       eslint.CLIEngine.outputFixes(res)
     }
 
@@ -142,19 +142,25 @@ function printLinterOutput(res, config, webpack) {
  */
 module.exports = function(input, map) {
   var webpack = this
+
+  var userOptions = assign(
+    // user defaults
+    this.options.eslint || {},
+    // loader query string
+    loaderUtils.getOptions(this)
+  )
+
   var config = assign(
     // loader defaults
     {
       formatter: require("eslint/lib/formatters/stylish"),
       cacheIdentifier: JSON.stringify({
         "eslint-loader": pkg.version,
-        eslint: eslint.version,
+        eslint: require(userOptions.eslintPath || "eslint").version,
       }),
+      eslintPath: "eslint",
     },
-    // user defaults
-    this.options.eslint || {},
-    // loader query string
-    loaderUtils.getOptions(this)
+    userOptions
   )
 
   var cacheDirectory = config.cache
@@ -166,6 +172,7 @@ module.exports = function(input, map) {
   // Create the engine only once per config
   var configHash = objectHash(config)
   if (!engines[configHash]) {
+    var eslint = require(config.eslintPath)
     engines[configHash] = new eslint.CLIEngine(config)
   }
 

test/eslint-path.js

@@ -0,0 +1,33 @@
+var path = require("path")
+var test = require("ava")
+var webpack = require("webpack")
+var conf = require("./utils/conf")
+
+test.cb("eslint-loader can use another instance of eslint via " +
+  "eslintPath config", function(t) {
+  t.plan(2)
+  webpack(conf(
+    {
+      entry: "./test/fixtures/good.js",
+    },
+    {
+      eslintPath: path.join(__dirname, "mock/eslint-mock.js"),
+    }
+  ),
+  function(err, stats) {
+    if (err) {
+      throw err
+    }
+
+    // console.log(stats.compilation.errors)
+    t.true(
+      stats.hasErrors(),
+      "a file that does not contains error but mock eslint instance " +
+      "returned error"
+    )
+    t.true(
+      stats.compilation.errors[0].message.indexOf("Fake error") > -1
+    )
+    t.end()
+  })
+})

test/mock/eslint-mock.js

@@ -0,0 +1,21 @@
+function CLIEngine() {
+
+}
+
+CLIEngine.prototype.executeOnText = function() {
+  return {
+    warningCount: 0,
+    errorCount: 1,
+    results: [{
+      messages: [
+        {
+          message: "Fake error",
+        },
+      ],
+    }],
+  }
+}
+
+module.exports = {
+  CLIEngine: CLIEngine,
+}