jest.config.js

/**
 * Code in the react-native ecosystem if often shipped untransformed, with flow or typescript in files
 * App code also needs to be transformed (it's TypeScript), but the rest of node_modules doesn't need to
 * Transforming the minimum amount of code makes tests run much faster
 *
 * If encountering a syntax error during tests with a new package, add it to this list
 */
const packagesToTransform = [
  'react-native',
  'react-native-(.*)',
  '@react-native',
  '@react-native-community',
  '@react-navigation',
  'expo',
  'expo-(.*)',
];

/** @type {import('@jest/types').Config.InitialOptions} */
const config = {
  /*
   * What the preset provides:
   * - a transformer to handle media assets (png, video)
   * - lots of mocks for react-native and expo modules
   */
  preset: 'jest-expo',
  // test environment setup
  globalSetup: '<rootDir>/src/testing/jest-globalSetup.ts',
  setupFiles: ['./src/testing/jest-setup.js'],
  setupFilesAfterEnv: ['./src/testing/jest-setupAfterEnv.js'],
  clearMocks: true,
  // module resolution
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
  moduleNameMapper: {
    // Keep in sync with babel.config.js and tsconfig.json
    '#app/(.*)': '<rootDir>/src/app/$1',
    '#modules/(.*)': '<rootDir>/src/modules/$1',
    '#shared/(.*)': '<rootDir>/src/shared/$1',
    '#testing/(.*)': '<rootDir>/src/testing/$1',
  },
  modulePaths: ['<rootDir>'],
  testRegex: '\\.test\\.[jt]sx?$',
  // module transformation
  transform: {
    // NOTE: If your projects uses special babel plugins, you'll need to go back to the slower default babel-jest setup
    '^.+\\.(js)$': '<rootDir>/node_modules/babel-jest',
  },
  transformIgnorePatterns: [
    `node_modules/(?!(${packagesToTransform.join('|')})/)`,
  ],
  cacheDirectory: '.cache/jest',
  // coverage
  collectCoverageFrom: ['src/**/*.{js,jsx,ts,tsx}'],
  coveragePathIgnorePatterns: ['/node_modules/'],
  // tools
  watchPlugins: [
    'jest-watch-typeahead/filename',
    'jest-watch-typeahead/testname',
  ],
  reporters: ['default', 'github-actions'], // Remove this line if your CI is not on Github actions
  snapshotResolver: './jestSnapshotResolver.js',
};

module.exports = config;