@repodog/jest-config

The Repodog Jest config.

Install package and peer dependencies

# terminal
npm install @repodog/jest-config @jest/globals jest suppress-experimental-warnings --save-dev

Install optional peer dependencies

# terminal
npm install babel-jest --save-dev
# or
npm install @swc/jest --save-dev

Use package

With Babel

// package.json
{
  "scripts": {
    // esm
    "test": "node --require=suppress-experimental-warnings --experimental-vm-modules node_modules/jest/bin/jest.js",
    // or cjs
    "test": "MODULE_SYSTEM=cjs node node_modules/jest/bin/jest.js"
  }
}

// jest.config.cjs
const jestConfig = require('@repodog/jest-config');

module.exports = {
  ...jestConfig(),
};

// .vscode/launch.json
{
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Jest - current file",
      "program": "${workspaceFolder}/node_modules/jest/bin/jest",
      "args": [
        "${relativeFile}"
      ],
      "env": {
        "DEBUG": "true",
        // esm
        "NODE_OPTIONS": "--experimental-vm-modules",
        // or cjs
        "MODULE_SYSTEM": "cjs"
      },
      "console": "integratedTerminal"
    }
  ]
}

With SWC

// package.json
{
  "scripts": {
    // esm
    "test": "COMPILER=swc node --require=suppress-experimental-warnings --experimental-vm-modules node_modules/jest/bin/jest.js",
    // or cjs
    "test": "COMPILER=swc MODULE_SYSTEM=cjs node node_modules/jest/bin/jest.js"
  }
}

// jest.config.cjs
const jestConfig = require('@repodog/jest-config');
const swcConfig = require('@repodog/swc-config');

module.exports = {
  ...jestConfig({ compilerOptions: swcConfig }),
};

// .vscode/launch.json
{
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Jest - current file",
      "program": "${workspaceFolder}/node_modules/jest/bin/jest",
      "args": [
        "${relativeFile}"
      ],
      "env": {
        "DEBUG": "true",
        "COMPILER": "swc",
        // esm
        "NODE_OPTIONS": "--experimental-vm-modules",
        // or cjs
        "MODULE_SYSTEM": "cjs"
      },
      "console": "integratedTerminal"
    }
  ]
}

Inline snapshots

The config includes prettier@^2 as a dependency so you can continue to use Jest inline snapshots without much additional configuration. All that is needed is to add a .prettierrc to the root of your project. This file will not conflict with the prettier.config.mjs file used by @repodog/eslint-config to format the rest of your code.

// .prettierrc
{
  "arrowParens": "avoid",
  "printWidth": 120,
  "singleQuote": true,
  "trailingComa": "all"
}

Environment variables

COMPILER = 'babel' || 'swc'

Uses either Babel or SWC to compile code for Jest. Default 'babel'.

MODULE_SYSTEM = 'esm' || 'cjs'

Sets the module sytem to either ESModules or commonjs. Default 'esm'.

DEBUG = 'true' || 'false'

Changes testMatch to cover all test files and disables the Jest timeout. These are useful to set when debugging a file in IDE. Default 'false'.

JS_ENV = 'web' || 'node'

When set to 'web', adds regexes to moduleNameMapper and transform to cater for .css and other file extensions Jest cannot resolve. Default 'node'.