webpack-espower-loader

2.0.0 verified Sat Apr 25 auth: no javascript

A webpack loader for power-assert that applies espower instrumentation to JavaScript sources during the webpack build process, enabling detailed assertion error messages (Power Assert) when tests fail. Current stable version is 2.0.0, with a 1.x branch for webpack 3 or lower. The loader is intended for use with webpack 4+; for webpack 3 or lower, use version 1.x. Key differentiator: it integrates Power Assert into webpack build pipelines, but note that it does not work with babel-loader (use babel-plugin-espower instead). The loader passes options through to espower.

Common errors

error Error: Module not found: Error: Cannot resolve module 'espower' ↓

cause espower is not installed as a peer dependency.

fix

Install espower: npm install --save-dev espower

error TypeError: Cannot read property 'replace' of undefined ↓

cause Loader options are undefined or null when passed to espower.

fix

Ensure options object is provided in webpack config (even if empty).

error Error: webpack-espower-loader only works with webpack 4+. For webpack 3 use version 1.x. ↓

cause Using webpack-espower-loader 2.x with webpack 3.

fix

Install webpack-espower-loader@1.0.2: npm install --save-dev webpack-espower-loader@1.0.2

Warnings

breaking webpack-espower-loader 2.x does not work with webpack 3 or lower. ↓

fix Use webpack-espower-loader@1.0.2 for webpack 3 or lower.

breaking webpack-espower-loader does not work with babel-loader (since babel 5). ↓

fix Use babel-plugin-espower instead of webpack-espower-loader when using babel-loader.

deprecated The 'pattern' option (singular) is deprecated in favor of 'patterns' (plural). ↓

fix Use 'patterns' in loader options.

gotcha The loader must be placed after transpilation loaders like babel-loader in the rule 'use' array. ↓

fix Ensure webpack-espower-loader runs after babel-loader in the loader chain.

gotcha Secure coding: The loader does not escape special characters in assertion expressions; ensure test inputs are safe to avoid injection. ↓

fix Sanitize or avoid dynamic generation of assertion messages from untrusted input.

Install

npm install webpack-espower-loader

yarn add webpack-espower-loader

pnpm add webpack-espower-loader

Quickstart

Configures webpack-espower-loader in webpack 4+ and shows a basic Power Assert test that produces enhanced assertion output.

// webpack.config.js
{
  module: {
    exprContextCritical: false,
    rules: [{
      test: /\.js$/,
      exclude: /node_modules/,
      use: {
        loader: 'webpack-espower-loader',
        options: {
          patterns: [
            'assert(value, [message])',
            'assert.ok(value, [message])',
            'assert.equal(actual, expected, [message])',
            'assert.notEqual(actual, expected, [message])',
            'assert.strictEqual(actual, expected, [message])',
            'assert.notStrictEqual(actual, expected, [message])',
            'assert.deepEqual(actual, expected, [message])',
            'assert.notDeepEqual(actual, expected, [message])'
          ]
        }
      }
    }]
  }
}

// test.js
const assert = require('power-assert');
assert.deepEqual([1,2,3], [1,2,4]); // outputs Power Assert diagnostics