Configuration

rjest reads configuration from your jest.config.js or jest.config.ts file.

Configuration File

rjest looks for configuration in this order:

1. jest.config.js
2. jest.config.ts
3. jest.config.mjs
4. jest.config.json
5. package.json (jest key)

Supported Options

Test Matching

testMatch

Glob patterns for test files:

module.exports = {
  testMatch: [
    '**/__tests__/**/*.ts',
    '**/*.test.ts',
    '**/*.spec.ts',
  ],
};

testRegex

Regex pattern for test files (alternative to testMatch):

module.exports = {
  testRegex: '(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$',
};

testPathIgnorePatterns

Patterns to exclude from testing:

module.exports = {
  testPathIgnorePatterns: [
    '/node_modules/',
    '/dist/',
    '/__fixtures__/',
  ],
};

Module Resolution

moduleFileExtensions

File extensions to consider:

module.exports = {
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json'],
};

moduleNameMapper

Map module paths:

module.exports = {
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/src/$1',
    '^~/(.*)$': '<rootDir>/src/$1',
  },
};

roots

Directories to search for tests:

module.exports = {
  roots: ['<rootDir>/src', '<rootDir>/tests'],
};

Setup Files

setupFiles

Scripts to run before test framework loads:

module.exports = {
  setupFiles: ['<rootDir>/setup/env.ts'],
};

setupFilesAfterEnv

Scripts to run after test framework loads:

module.exports = {
  setupFilesAfterEnv: ['<rootDir>/setup/jest.setup.ts'],
};

Example setup file:

jest.setup.ts

// Add custom matchers
expect.extend({
  toBeWithinRange(received, floor, ceiling) {
    const pass = received >= floor && received <= ceiling;
    return {
      message: () => `expected ${received} to be within range ${floor} - ${ceiling}`,
      pass,
    };
  },
});

Test Behavior

testTimeout

Default timeout for tests (milliseconds):

module.exports = {
  testTimeout: 5000, // 5 seconds
};

bail

Stop after first failure:

module.exports = {
  bail: true,
  // or specify number of failures
  bail: 3,
};

Mock Behavior

clearMocks

Clear mock calls between tests:

module.exports = {
  clearMocks: true,
};

resetMocks

Reset mock state between tests:

module.exports = {
  resetMocks: true,
};

restoreMocks

Restore original implementations between tests:

module.exports = {
  restoreMocks: true,
};

Snapshot

snapshotSerializers

Custom snapshot serializers:

module.exports = {
  snapshotSerializers: ['my-custom-serializer'],
};

Example Configurations

TypeScript Project

jest.config.js

module.exports = {
  testMatch: ['**/*.test.ts', '**/*.test.tsx'],
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json'],
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/src/$1',
  },
  setupFilesAfterEnv: ['<rootDir>/jest.setup.ts'],
  testPathIgnorePatterns: ['/node_modules/', '/dist/'],
};

Monorepo

jest.config.js

module.exports = {
  roots: ['<rootDir>/packages'],
  testMatch: ['**/src/**/*.test.ts'],
  moduleNameMapper: {
    '^@myorg/(.*)$': '<rootDir>/packages/$1/src',
  },
};

Minimal Configuration

jest.config.js

module.exports = {
  testMatch: ['**/*.test.ts'],
};

Options Not Supported

These Jest options are not yet supported:

Option	Status
transform	Not needed (built-in SWC)
preset	Not supported
testEnvironment	Only Node environment
coverageThreshold	Coverage not implemented
globalSetup	Not supported
globalTeardown	Not supported
projects	Not supported
reporters	Only default reporter

TypeScript Configuration

For TypeScript config files:

jest.config.ts

import type { Config } from 'jest';

const config: Config = {
  testMatch: ['**/*.test.ts'],
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx'],
};

export default config;

Note

rjest compiles jest.config.ts automatically using the built-in SWC compiler.