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,

  // An array of glob patterns indicating a set of files for which coverage information should be collected
  collectCoverageFrom: ['src/**/*.{js,jsx,mjs}'],

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

  // An array of file extensions your modules use
  moduleFileExtensions: ['js', 'json', 'jsx'],

  // Bundle mapper for d3 import and other custom mocks
  moduleNameMapper: {
    d3: '<rootDir>/node_modules/d3/dist/d3.min.js',
    'react-leaflet': '<rootDir>/src/_tests_/__mocks__/react-leaflet.js',
    'marker-cluster-group': '<rootDir>/src/_tests_/__mocks__/react-leaflet-cluster.js',
    '\\.(css|less|scss|sass)$': 'identity-obj-proxy', // <-- Added to mock CSS/SCSS files
  },

  // The paths to modules that run some code to configure or set up the testing environment before each test
  setupFiles: ['<rootDir>src/setupTests.js'],

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

  // The glob patterns Jest uses to detect test files
  testMatch: ['**/__tests__/**/*.js?(x)', '**/?(*.)+(spec|test).js?(x)'],

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

  // This option sets the URL for the jsdom environment. It is reflected in properties such as location.href
  testURL: 'http://localhost',

  // An array of regexp pattern strings that are matched against all source file paths, matched files will skip transformation
  transformIgnorePatterns: ['/node_modules/(?!d3|d3-array|internmap|delaunator|robust-predicates)'],

  // Include snapshot serializers
  snapshotSerializers: ['enzyme-to-json/serializer'],

  // Indicates whether each individual test should be reported during the run
  verbose: false,
};