jest

> Jest configuration with ts-jest, coverage thresholds and sensible defaults.

> 🛠️ Maintenance mode: dependency and security updates only. New projects should use @jmlweb/vitest-config.

✨ Features

🔧 TypeScript: ts-jest transform out of the box
📊 Coverage: 80% global thresholds, text/json/html reporters
🎯 Sensible defaults: Node environment, mocks cleared and restored between tests
🚀 Configurable: createJestConfig() factory with typed options

📦 Installation

npm install --save-dev @jmlweb/jest-config jest ts-jest @types/jest

> 💡 Upgrading? See the Migration Guide.

🚀 Quick Start

import jestConfig from '@jmlweb/jest-config';

export default jestConfig;

With a TypeScript config file (jest.config.ts), Jest also needs ts-node.

💡 Examples

Factory with options

import { createJestConfig } from '@jmlweb/jest-config';

export default createJestConfig({
  testEnvironment: 'jsdom',
  setupFilesAfterEnv: ['<rootDir>/src/test/setup.ts'],
  moduleNameMapper: { '^@/(.*)$': '<rootDir>/src/$1' },
});

jsdom needs jest-environment-jsdom installed.

Custom coverage thresholds

import { createJestConfig } from '@jmlweb/jest-config';

export default createJestConfig({
  coverageThreshold: {
    global: { lines: 90, functions: 90, branches: 85, statements: 90 },
  },
});

Spread the base config

import jestConfig from '@jmlweb/jest-config';

export default {
  ...jestConfig,
  testTimeout: 10000,
};

📋 Configuration Details

createJestConfig(options) options and defaults:

Option	Default
`testEnvironment`	`'node'`
`moduleFileExtensions`	`['ts', 'tsx', 'js', 'jsx', 'json']`
`testMatch`	`['*/.{test,spec}.{ts,tsx,js,jsx}']`
`testPathIgnorePatterns`	`/node_modules/`, `/dist/`, `/build/`, `/.git/`, `/.cache/`
`collectCoverageFrom`	`['src/*/.{ts,tsx,js,jsx}']`
`coveragePathIgnorePatterns`	node_modules, dist, build, coverage, `.d.ts`, config, test and spec files
`coverageThreshold`	`global`: 80 for lines, functions, branches, statements
`coverageReporters`	`['text', 'json', 'html']`
`setupFilesAfterEnv`	`[]` (omitted when empty)
`moduleNameMapper`	`{}` (omitted when empty)
`transform`	`ts-jest` for `.ts`/`.tsx` with `esModuleInterop` and `allowSyntheticDefaultImports`
`testTimeout`	`5000`

Fixed settings: collectCoverage: false (use --coverage), verbose: true, clearMocks: true, restoreMocks: true, resetModules: false.

🎯 When to Use

✅ Existing Jest projects with TypeScript
✅ Shared coverage baseline

Not for you if you are starting a new project: use @jmlweb/vitest-config.

🔧 Extending the Configuration

Pass options to createJestConfig, or spread the result and override. Passing transform replaces the default entirely, so include the ts-jest entry again if you still need it.

📝 Usage with Scripts

{
  "scripts": {
    "test": "jest",
    "test:watch": "jest --watch",
    "test:coverage": "jest --coverage"
  }
}

📋 Requirements

Node.js >= 22.12.0
Jest >= 29.0.0
ts-jest >= 29.0.0

📦 Peer Dependencies

jest (>=29.0.0)
ts-jest (>=29.0.0)
@types/jest (>=29.0.0)

@jmlweb/vitest-config - Recommended replacement
@jmlweb/tsconfig-base - TypeScript configuration
@jmlweb/oxlint-config-base - Oxlint config

🔄 Migration Guide

1.x to 2.0

Breaking: Node.js >= 22.12.0 is required.

Upgrade Node.js to 22.12.0 or later.
Update: npm install --save-dev @jmlweb/jest-config@latest

See the Changelog for details.

📄 License

MIT