feature #19 Allow to add extra plugin (alOneh)

This PR was squashed before being merged into the master branch (closes #19).

Discussion
----------

Allow to add extra plugin

Encore does not support adding an extra plugin to the list of registered plugins.
In Symfony demo, we try to reduce the size of one of our entries and have to manually add the plugin to the config by doing this :

```js
var config = Encore.getWebpackConfig();
config.plugins.push(new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/));
```

I propose to update the API of Encore through a new method `addPlugin(plugin)`.

```js
Encore
// ...
    .addPlugin(new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/))
```

Commits
-------

dbe7ea2 Merge branch 'master' into add-plugins
225a0da Allow to add extra plugin

Author: weaverryan

index.js

@@ -135,6 +135,21 @@ module.exports = {
         return this;
     },
 
+    /**
+     * Add a plugin to the sets of plugins already registered by Encore
+     *
+     * For example, if you want to add the "webpack.IgnorePlugin()", then:
+     *      .addPlugin(new webpack.IgnorePlugin(requestRegExp, contextRegExp))
+     *
+     * @param {string} plugin
+     * @return {exports}
+     */
+    addPlugin(plugin) {
+        webpackConfig.addPlugin(plugin);
+
+        return this;
+    },
+
     /**
      * Adds a custom loader config
      *

lib/WebpackConfig.js

@@ -36,6 +36,7 @@ class WebpackConfig {
         this.manifestKeyPrefix = null;
         this.entries = new Map();
         this.styleEntries = new Map();
+        this.plugins = [];
         this.useVersioning = false;
         this.useSourceMaps = false;
         this.usePostCssLoader = false;
@@ -158,6 +159,10 @@ class WebpackConfig {
         this.styleEntries.set(name, src);
     }
 
+    addPlugin(plugin) {
+        this.plugins.push(plugin);
+    }
+
     addLoader(loader) {
         this.loaders.push(loader);
     }

lib/config-generator.js

@@ -411,6 +411,10 @@ class ConfigGenerator {
             plugins.push(new AssetOutputDisplayPlugin(outputPath, friendlyErrorsPlugin));
         }
 
+        this.webpackConfig.plugins.forEach(function(plugin) {
+            plugins.push(plugin);
+        });
+
         return plugins;
     }
 

test/WebpackConfig.js

@@ -14,6 +14,7 @@ const WebpackConfig = require('../lib/WebpackConfig');
 const RuntimeConfig = require('../lib/config/RuntimeConfig');
 const path = require('path');
 const fs = require('fs');
+const webpack = require('webpack');
 
 function createConfig() {
     const runtimeConfig = new RuntimeConfig();
@@ -277,6 +278,19 @@ describe('WebpackConfig object', () => {
         });
     });
 
+    describe('addPlugin', () => {
+        it('extends the current registered plugins', () => {
+            const config = createConfig();
+            const nbOfPlugins = config.plugins.length;
+
+            expect(nbOfPlugins).to.equal(0);
+
+            config.addPlugin(new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/));
+
+            expect(config.plugins.length).to.equal(1);
+        });
+    });
+
     describe('addLoader', () => {
         it('Adds a new loader', () => {
             const config = createConfig();

test/config-generator.js

@@ -500,4 +500,18 @@ describe('The config-generator function', () => {
             expect(actualConfig.devServer.publicPath).to.equal('/subdirectory/build/');
         });
     });
+
+    describe('test for addPlugin config', () => {
+        it('extra plugin is set correctly', () => {
+            const config = createConfig();
+            config.outputPath = '/tmp/public/build';
+            config.setPublicPath('/build/');
+            config.addPlugin(new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/));
+
+            const actualConfig = configGenerator(config);
+
+            const ignorePlugin = findPlugin(webpack.IgnorePlugin, actualConfig.plugins);
+            expect(ignorePlugin).to.not.be.undefined;
+        });
+    });
 });