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Webpack bundles tests (enzyme / jest) in the production env

I have issue with Webpack building production bundle with test files + test libs included.
In this case it is Enzyme and Jest which we use.
Webpack version 3.10.0
Webpack.build.js
const path = require('path');
const webpack = require('webpack');
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
module.exports = function() {
return {
entry: './src/index.js',
output: {
path: path.resolve(__dirname, '../build'),
filename: 'bundle.js',
},
module: {
rules: [
{
test: /\.js$/,
exclude: [
/node_modules/,
/__snapshots__/,
/test-util/,
],
loader: 'babel-loader'
},
{
test: /\.scss$/,
use: [
{
loader: 'isomorphic-style-loader'
},
{
loader: 'css-loader'
},
{
loader: 'sass-loader'
}
]
},
]
},
plugins: [
new UglifyJsPlugin(),
new webpack.DefinePlugin({
'process.env': {
'NODE_ENV': JSON.stringify(process.env.NODE_ENV),
}
}),
]
}
};
Here is the file structure
I have tried to workaround the issue by placing Enzyme as external resource in webpack.
externals: {
'enzyme': 'enzyme',
'enzyme-adapter-react-16': 'enzyme-adapter-react-16',
}
That does exclude it from build but (it is workaround) it still builds the snapshot files
I have tried to make "test" regex of babel-loader more specific and exclude test files but it failed.
This is new project and I spent whole day trying to make it bundle only what is necesary. Drained all of my know-how, my google know-how and know-how of the poeple I know or I work with. Hope that SO will be smarter :)

Webpack throws TypeError: Super expression must either be null or a function, not undefined when importing LESS file

I have the following in a file initialize.js:
import App from './components/App';
import './styles/application.less';
document.addEventListener('DOMContentLoaded', () => {
const app = new App();
app.start();
});
In webpack.config.js I have:
'use strict';
const path = require('path');
const webpack = require('webpack');
const merge = require('webpack-merge');
const ProvidePlugin = webpack.ProvidePlugin;
const ModuleConcatenationPlugin = webpack.optimize.ModuleConcatenationPlugin;
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const extractLess = new ExtractTextPlugin({
filename: 'app.css',
});
const webpackCommon = {
entry: {
app: ['./app/initialize']
},
module: {
rules: [{
test: /\.js$/,
exclude: /node_modules/,
use: [{
loader: 'babel-loader?presets[]=es2015'
}]
}, {
test: /\.hbs$/,
use: {
loader: 'handlebars-loader'
}
}, {
test: /\.less$/,
exclude: /node_modules/,
use: extractLess.extract({
use: [{
loader: 'css-loader'
}, {
loader: 'less-loader'
}],
// use style-loader in development
fallback: 'style-loader'
}),
}]
},
output: {
filename: 'app.js',
path: path.join(__dirname, './public'),
publicPath: '/'
},
plugins: [
extractLess,
new CopyWebpackPlugin([{
from: './app/assets/index.html',
to: './index.html'
}]),
new ProvidePlugin({
$: 'jquery',
_: 'underscore'
}),
new ModuleConcatenationPlugin(),
],
};
module.exports = merge(webpackCommon, {
devtool: '#inline-source-map',
devServer: {
contentBase: path.join(__dirname, 'public'),
compress: true,
port: 9000
}
});
I tried removing the the plugins and the contents of application.less, but I keep getting this error:
ERROR in ./node_modules/css-loader!./node_modules/less-loader/dist/cjs.js!./app/styles/application.less
Module build failed: TypeError: Super expression must either be null or a function, not undefined
at ...
# ./app/styles/application.less 4:14-127
# ./app/initialize.js
If I replace that LESS file with a CSS one and update the config it works fine, so I guess the problem has to do with less-loader.
I'm using Webpack 3.4.1, Style Loader 0.18.2, LESS Loader 4.0.5, Extract Text Webpack Plugin 3.0.0 and CSS Loader css-loader.

My bad, I didn't notice I was using an old less version. That was the culprit. Just updated it to 2.7.2 and the problem is gone.

Error in React: unknown word when using webpack

I have set up a React environment with webpack and babel. However, when I run webpack-dev-server --progress --colors, I get error like this:
ERROR in multi (webpack)-dev-server/client?http://localhost:8080 E:/src/index.js
Module not found: Error: can't resolve 'E:\src/index.js' in 'E:\personal_projects\web-site-name'
...
(2:1) Unknown word
1: var url = require("url");
^
My webpack.config.js file is this:
var webpack = require('webpack');
var path = require('path');
var BUILD_DIR = path.resolve(__dirname, '/public');
var APP_DIR = path.resolve(__dirname, '/src');
var config = {
entry: APP_DIR + '/index.js',
output: {
path: BUILD_DIR,
filename: 'bundle.js'
},
module: {
rules: [
{
test: /\.js$/,
exclude: /(node_modules|bower_components)/,
use: {
loader: 'babel-loader',
options: {
presets: ['env']
}
}
},
{
test: /(\.css$)/,
loaders: ['style-loader', 'css-loader', 'postcss-loader']
},
{
loader: 'postcss-loader',
options: {
plugins: () => [require('autoprefixer')]
}
}
]
}
};
module.exports = config;
I think there is some problem with babel and it compiling my index.js to my bundle.js file. Any advice on this?

You either need to use path.join or remove your slashes, e.g.
path.resolve(__dirname, '/src');
and other lines using resolve should be
path.resolve(__dirname, 'src');
or
path.join(__dirname, 'src');
or even
path.join(__dirname, '/src');
Your usage of .resolve passes an absolute path /src, meaning that the first argument is essentially discarded.

Run Mocha specs from React app in a browser using Webpack and mocha-loader

I have a react App for which I'd like to run its mocha specs (unit-tests) in a browser. I found this SO post and tried to apply same idea to my project. I came up with the following webpack config file:
webpack.config.test.js
const nodeExternals = require('webpack-node-externals');
const path = require('path');
const host = 'localhost';
const port = '8084';
module.exports = {
target: 'web',
externals: [nodeExternals()],
entry: './specs/index.js',
output: {
filename: 'debug.bundle.js',
path: path.join(__dirname, 'tests'),
publicPath: `http://${host}:${port}/tests`,
},
devServer: {
host,
port,
},
module: {
rules: [
{
test: /\.js$/,
loaders: ['react-hot-loader', 'babel-loader'],
enforce: 'pre',
},
{
test: /.+Spec\.js$/,
loaders: ['mocha-loader'],
},
{
test: /(\.css|\.scss)$/,
loader: 'null-loader',
exclude: [
/build/,
],
},
{
test: /(\.jpg|\.jpeg|\.png|\.gif)$/,
loader: 'null-loader',
},
],
},
};
And, after starting the server with:
webpack-dev-server --config webpack.config.test.js
I get the following error in console:
I've read that the problem might be with webpack-node-externals but not really sure what's happening. Any ideas?

I think you will want to use webpack-node-externals only when you bundle files for backend (as described in plugin README). When you use it you forbid it to build all modules from node_modules folder.

Still getting 'Symbol' is undefined' error even after adding babel-polyfill in my webpack

https://babeljs.io/docs/usage/polyfill/#usage-in-browser
I did not understand the lines on the documentation page under:
Usage in Browser heading
can someone help me with what else is required:
Below are my code snippets:
I'm using storybook as a boilerplate:
webpack.config.js file:
entry: [
'babel-polyfill',
require.resolve('react-dev-utils/webpackHotDevClient'),
paths.appIndexJs
]
index.js file:
import 'babel-polyfill';
import React from 'react';
Is there some other files also where I need to add babel-polyfill related code.
require('babel-polyfill');
var path = require('path');
var autoprefixer = require('autoprefixer');
var webpack = require('webpack');
var HtmlWebpackPlugin = require('html-webpack-plugin');
var CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
var InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
var WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
var getClientEnvironment = require('./env');
var paths = require('./paths');
var publicPath = '/';
var publicUrl = '';
var env = getClientEnvironment(publicUrl);
module.exports = {
devtool: 'cheap-module-source-map',
entry: ['babel-polyfill',
require.resolve('react-dev-utils/webpackHotDevClient'),
require.resolve('./polyfills'),
paths.appIndexJs
],
output: {
path: paths.appBuild,
pathinfo: true,
filename: 'static/js/bundle.js',
publicPath: publicPath
},
resolve: {
fallback: paths.nodePaths,
extensions: ['.js', '.json', '.jsx', ''],
alias: {
'react-native': 'react-native-web'
}
},
module: {
// First, run the linter.
// It's important to do this before Babel processes the JS.
preLoaders: [{
test: /\.(js|jsx)$/,
loader: 'eslint',
include: paths.appSrc,
}],
loaders: [{
exclude: [/\.html$/, /\.(js|jsx)$/, /\.css$/, /\.json$/],
loader: 'url',
query: {
limit: 10000,
name: 'static/media/[name].[hash:8].[ext]'
}
},
// Process JS with Babel.
{
test: /\.(js|jsx)$/,
include: paths.appSrc,
loader: 'babel',
query: {
cacheDirectory: true
}
}, {
test: /\.css$/,
loader: 'style!css?importLoaders=1!postcss'
}, {
test: /\.json$/,
loader: 'json'
}
]
},
// We use PostCSS for autoprefixing only.
postcss: function() {
return [
autoprefixer({
browsers: ['>1%', 'last 4 versions', 'Firefox ESR', 'not ie < 9', // React doesn't support IE8 anyway
]
}),
];
},
plugins: [
new InterpolateHtmlPlugin({
PUBLIC_URL: publicUrl
}),
new HtmlWebpackPlugin({
inject: true,
template: paths.appHtml,
}),
new webpack.DefinePlugin(env),
new webpack.HotModuleReplacementPlugin(),
new CaseSensitivePathsPlugin(),
new WatchMissingNodeModulesPlugin(paths.appNodeModules)
],
node: {
fs: 'empty',
net: 'empty',
tls: 'empty'
}
};

There are two ways to get this code into your browser.
1 - Include the babel-polyfill module in the webpack bundle
2 - Load it as an external script in your html
Webpack - adding bundle dependencies with entry arrays
Put an array as the entry point to make the babel-polyfill module available to your bundle as an export.
With webpack.config.js, add babel-polyfill to your entry array.
The webpack docs explain how an entry array is handled:
What happens when you pass an array to entry? Passing an array of file
paths to the entry property creates what is known as a "multi-main
entry". This is useful when you would like to inject multiple
dependent files together and graph their dependencies into one
"chunk".
Webpack.config.js
require("babel-polyfill");
var config = {
devtool: 'cheap-module-eval-source-map',
entry: {
main: [
// configuration for babel6
['babel-polyfill', './src/js/main.js']
]
},
}
Alternative to Webpack - load babel-polyfill as an external script in the browser html
The alternative to using webpack would mean including the module as an external script in your html. It will then be available to code in the browser but the webpack bundle won't be directly aware of it.
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/babel-polyfill/6.22.0/polyfill.js"></script>