feat: move webpack to a peer dependency and allow webpack 2 (#46)

* test: test against both webpack 1 and webpack 2

* chore: use npm install version

* style: whitespace

package.json

@@ -27,27 +27,31 @@
   ],
   "homepage": "https://github.com/vieron/stylelint-webpack-plugin#readme",
   "peerDependencies": {
-    "stylelint": "^7.7.0"
+    "stylelint": "^7.7.0",
+    "webpack": "^2 || ^2.2.0-rc.0 || ^2.1.0-beta.0 || ^1.13.2"
   },
   "dependencies": {
     "arrify": "^1.0.1",
     "chalk": "^1.1.3",
     "object-assign": "^4.1.0",
-    "stylelint": "^7.7.0",
-    "webpack": "^1.13.2"
+    "stylelint": "^7.7.0"
   },
   "devDependencies": {
     "chai": "^3.5.0",
     "chai-as-promised": "^6.0.0",
     "coveralls": "^2.11.14",
     "memory-fs": "^0.3.0",
     "mocha": "^3.1.0",
+    "npm-install-version": "^6.0.1",
     "nyc": "^8.3.1",
+    "webpack": "^1.13.2",
     "xo": "^0.16.0"
   },
   "scripts": {
     "pretest": "xo",
-    "test": "nyc mocha",
+    "test:webpack1": "WEBPACK_VERSION=1 nyc mocha",
+    "test:webpack2": "WEBPACK_VERSION=beta nyc mocha",
+    "test": "npm run test:webpack1 && npm run test:webpack2",
     "preversion": "npm run test",
     "version": "git add -A ."
   },

test/helpers/pack.js

@@ -1,7 +1,7 @@
 'use strict';
 
-var webpack = require('webpack');
 var MemoryFileSystem = require('memory-fs');
+var webpack = require('./webpack');
 
 /**
  * Basic in memory compiler, promisified

test/helpers/webpack.js

@@ -0,0 +1,8 @@
+'use strict';
+
+var niv = require('npm-install-version');
+
+var packageName = 'webpack@' + process.env.WEBPACK_VERSION;
+niv.install(packageName);
+
+module.exports = niv.require(packageName);

test/index.js

@@ -1,14 +1,13 @@
 'use strict';
 
 var assign = require('object-assign');
-var webpack = require('webpack');
 
 var StyleLintPlugin = require('../');
 var pack = require('./helpers/pack');
+var webpack = require('./helpers/webpack');
 
 var configFilePath = getPath('./.stylelintrc');
 var baseConfig = {
-  debug: false,
   output: {
     path: getPath('output')
   },
@@ -20,6 +19,16 @@ var baseConfig = {
   ]
 };
 
+if (typeof webpack.LoaderOptionsPlugin === 'undefined') {
+  baseConfig.debug = false;
+} else {
+  baseConfig.plugins.push(
+    new webpack.LoaderOptionsPlugin({
+      debug: false
+    })
+  );
+}
+
 describe('stylelint-webpack-plugin', function () {
   it('works with a simple file', function () {
     var config = {