mocha-webpack

library1.1.0jsnpmunverified

A CLI tool that integrates Mocha test runner with Webpack bundling, allowing you to test modules that rely on Webpack features (loaders, plugins, resolve aliases) without pre-building or using hacks. Version 1.1.0 is the latest stable release (as of late 2018). It supports Mocha >=2.4.5 <=5 and Webpack 2.x/3.x. Key differentiators: bundling tests into a single bundle with Webpack's full pipeline (loaders, resolve, plugins), built-in source map support, memory-fs for speed (no disk writes), customizable file watcher, and support for multiple entry files/patterns. The project is effectively unmaintained (last release 2017) for Webpack 4+ compatibility.

testing devops

npm install mocha-webpack

github ↗package ↗

INSTALL

IMPORT

SIG · MOCHA-WEBPACK

mocha-webpack

testingjavascriptv1.1.0

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

mocha-webpack

✓ npx mocha-webpack --webpack-config webpack.config.js test/**/*.spec.js

✗ mocha-webpack --require source-map-support/register test/**/*.spec.js

mocha-webpack includes source-map-support by default since v1.0.0. CLI usage only; no programmatic API exported.

mocha-webpack (require from Node)

✓ import 'mocha-webpack'; // or require('mocha-webpack') — only side effects

✗ const { run } = require('mocha-webpack');

mocha-webpack does not export any functions or objects; requiring it merely registers the CLI command. Use CLI arguments instead.

Configures mocha-webpack with a webpack config file, custom opts file, and runs tests matching a glob pattern.

// package.json scripts { "scripts": { "test": "mocha-webpack --webpack-config webpack.test.js --opts ./mocha-webpack.opts test/**/*.spec.js" } } // mocha-webpack.opts --timeout 10000 --reporter spec // webpack.test.js (example) const path = require('path'); module.exports = { mode: 'development', resolve: { extensions: ['.js', '.jsx', '.json'] }, module: { rules: [ { test: /\.jsx?$/, exclude: /node_modules/, use: { loader: 'babel-loader', options: { presets: ['@babel/preset-env', '@babel/preset-react'] } } } ] } }; // Run: npx mocha-webpack --webpack-config webpack.test.js test/**/*.spec.js

mocha-webpack --version

Debug

Known issues

deprecatedmocha-webpack is unmaintained since v1.1.0 (2017). No Webpack 4/5 compatibility. Use mochapack or webpack-shell-plugin instead.

fix

Migrate to mochapack (https://github.com/sysgears/mochapack) or configure webpack+mocha manually.

affects: >=1.0.0

breakingv1.0.0 switched from writing bundle to disk to using memory-fs. If you relied on the generated bundle file, it no longer exists.

fix

Remove any references to generated bundle file. Use --webpack-config to specify output settings or rely on memory-fs.

affects: >=1.0.0 <1.0.0

breakingv1.0.0 replaced 'glob-like' file resolution with real glob. Patterns like 'test/unit/*' may resolve differently if `resolve.extensions` not set.

fix

Ensure webpack resolve.extensions includes '.js' and other extensions used in your tests.

affects: >=1.0.0 <1.0.0

gotchamocha-webpack will ignore webpack's `entry` and `output` configuration; it overrides them internally. Do not set them in your webpack config, or they will be overwritten.

fix

Omit `entry` and `output` from your webpack test config, or use `--webpack-config` that merges partial configs.

affects: *

gotchaWebpack 4 is not supported. Attempting to use mocha-webpack with webpack@4 will fail at module resolution.

fix

Use webpack@3.x or switch to mochapack (supports webpack 4+).

affects: >=1.0.0

deprecatedThe `--opts` flag defaults to looking for `mocha-webpack.opts` or `mocha.opts` in the current directory. If you have both, mocha-webpack prefers `mocha-webpack.opts`.

fix

Rename your opts file to `mocha-webpack.opts` or use `--opts path/to/your.opts`.

affects: >=0.3.0

Errors

Common errors & fixes

Error: Cannot find module 'mocha-webpack' from '<PROJECT>' at Function.module.exports [as runMain] (module.js:xxx:xx)

Mocha-webpack is not installed globally or locally when running via CLI.

fix

Install mocha-webpack locally: `npm install --save-dev mocha-webpack` and use npx or package.json scripts.

Error: webpack.optimize.OccurrenceOrderPlugin is not a constructor

Using mocha-webpack with webpack 4, which removed deprecated plugins.

fix

Downgrade to webpack@3 or migrate to mochapack.

TypeError: Cannot read property 'getFiles' of undefined

This error appears in v1.0.1 and was fixed; related to file resolution issues.

fix

Update to mocha-webpack@1.1.0 which fixed this bug.

Error: Module not found: Error: Can't resolve 'fs' in '<PROJECT>/node_modules/mocha-webpack'

Webpack target/node misconfiguration; mocha-webpack expects Node environment.

fix

Set webpack target to 'node' in your webpack config: `target: 'node'`.

Upgrade

Version history

1.1.0latest on npm

Audit

Dependencies

mocharequiredpeer dependency: test runner framework

webpackrequiredpeer dependency: module bundler for test compilation

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/zinserjan/mocha-webpack ↗

packagehttps://www.npmjs.com/package/mocha-webpack ↗