js-cjs

js-cjs runs JavaScript tests as CommonJS in the node environment. jest-esm-transformer-2 transforms JavaScript, including ESM packages in node_modules.

Usage

module.exports = {
  preset: '@repobuddy/jest/presets/js-cjs',
}

Options

None. A preset takes no options.

Effective config

Printed from the built preset with Node.js 26, in a directory that has a src folder:

{
  transform: {
    '\\.m?jsx?$': 'jest-esm-transformer-2',
  },
  transformIgnorePatterns: [],
  collectCoverageFrom: [
    '<rootDir>/src/**/*.{js,jsx,cjs,mjs,ts,tsx,cts,mts}',
    '!<rootDir>/src/**/*.stories.*',
  ],
  roots: ['<rootDir>/src'],
  coveragePathIgnorePatterns: [
    '\\.(spec|test|unit|accept|integrate|learning|system|perf|stress|load)(\\..*)?\\.(js|jsx|cjs|mjs|ts|tsx|cts|mts)$',
  ],
  testEnvironment: 'node',
  testRegex: [
    '\\.(spec|test|unit|accept|integrate|learning|system|perf|stress)(\\.node)?\\.(js|jsx|cjs|mjs|ts|tsx|cts|mts)$',
    '\\.(spec|test|unit|accept|integrate|learning|system|perf|stress)\\.node14\\.(js|jsx|cjs|mjs|ts|tsx|cts|mts)$',
    // one entry per Node.js major, from 15 up to the running major
  ],
}

It is built from configs.jsCjs, configs.configSource(), and configs.node.

Packages it needs

extract.extractPackages() on the preset returns:

['jest-environment-node', 'jest-esm-transformer-2']

Behavior

transformIgnorePatterns: [] makes Jest transform files in node_modules. In the js-cjs fixture, require('chalk').default loads chalk 6, an ESM-only package.
The transform pattern matches .js, .jsx, .mjs, and .mjsx. .cjs files are not transformed.
Test file names: see test file names.

`js-cjs-watch` variant

@repobuddy/jest/presets/js-cjs-watch is js-cjs plus the watch plugins of the watch preset.

Examples

The js-cjs fixture keeps its source in source/, which the preset detects:

module.exports = {
  preset: '@repobuddy/jest/presets/js-cjs-watch',
  detectOpenHandles: true,
}