ycw / e2edce

Deadcode elimination via running end-to-end tests.

About

Deadcode elimination via running end-to-end tests.

Sample project: DCE for threejs

Install

npm i -D ycw/e2edce

Usage

First, create a configuration file in project root

Then, config package.json

{ 
  "scripts": {
    "build": "e2edce e2edce.config.js"
  }
}

Finally, run npm run build to build artifacts

• index.build.js (min)
• index.build.js.gz (min + gzipped)

Configuration File

e2edce.config.js

export default {
  // --- required ---
  configs: [ // array of configs
    {
      // --- required ---
      input: 'src/index.js', // path to entry
      output: 'index.build.js', // path to output file
      test: 'e2e/test.js', // path to test file 
      // --- optional ---
      compress: true, 
      mangle: true,
      beautify: false, // with indentation?
      debug: false, // create a debug build?
      port: 8081, // dev server port
      headless: true, // run tests in headless browser?
      visitor: undefined, // transform sources 
    }
  ],
  // --- optional ---
  setup: async() => {}, // run once before processing
  teardown: async() => {}, // run once after processing
  resolve: async() => {}, // custom module resolution
}

• compress is https://github.com/terser/terser#compress-options

• mangle is https://github.com/terser/terser#mangle-options

• beautify is the opposite of 'minified' in https://babeljs.io/docs/en/babel-generator

• debug if true, uncoverage fns will throw at runtime instead of removal at compile time; compress, mangle and beautify will be overrided.

• resolve is https://rollupjs.org/guide/en/#resolveid

  We could generate temporary modules(in setup) for module replacement(in resolve) and remove those modules(in teardown) after processing all builds.

• visitor is a babel visitor

  This will transform original sources during flattening.

Test File

e2e/test.js

Export a async fn or an object

export default async (page) => { // e2e test
  await page.goto('http://localhost:8081', { waitUntil: 'networkidle' })
}

export default {
  // --- required ---
  test: async () => { // e2e test
    await page.goto('http://localhost:8081', { waitUntil: 'networkidle' })
  },
  // --- optional ---
  inject: () => {}
}

• page is a https://playwright.dev/docs/api/class-page

• inject, a fn to be injected at the end of input module

  We could add mocks inside inject() to directly cover certain code branches instead of writing complex e2e tests inside test()