jest.config.js

// For a detailed explanation regarding each configuration property, visit:
// https://jestjs.io/docs/en/configuration.html

module.exports = {
  // Automatically clear mock calls and instances between every test
  clearMocks: true,

  // Indicates whether the coverage information should be collected while executing the test
  collectCoverage: true,

  collectCoverageFrom: ['src/**/*.js'],

  // The directory where Jest should output its coverage files
  coverageDirectory: './.coverage/',

  // An array of regexp pattern strings used to skip coverage collection
  coveragePathIgnorePatterns: ['/node_modules/', '/dist/', '/playground/'],

  // An array of file extensions your modules use
  moduleFileExtensions: ['ts', 'tsx', 'js', 'json', 'node', 'mjs'],

  // The test environment that will be used for testing
  testEnvironment: 'node',

  // An array of regexp pattern strings that are matched against all test paths, matched tests are skipped
  testPathIgnorePatterns: ['/node_modules/'],

  // The regexp pattern Jest uses to detect test files
  testRegex: '.*\\.test\\.js$',

  // A map from regular expressions to paths to transformers
  transform: {
    '^.+\\.js$': 'babel-jest',
  },
};