jest.config.js

const supportsESM = parseInt(process.versions.node) >= 12;

// These tests files are directly importing `src` files rather than the compiled versions
const importsSrc = [
  "packages/babel-parser/test/unit/tokenizer/types.js",
  "packages/babel-parser/test/unit/util/identifier.js",
  "packages/babel-parser/test/unit/util/location.js",
  "packages/babel-plugin-bugfix-safari-id-destructuring-collision-in-function-expression/test/util.test.js",
  "packages/babel-plugin-bugfix-v8-spread-parameters-in-optional-chaining/test/util.test.js",
  "packages/babel-plugin-proposal-optional-chaining/test/util.test.js",
  "packages/babel-preset-react/test/normalize-options.spec.js",
  "packages/babel-preset-typescript/test/normalize-options.spec.js",
];

module.exports = {
  runner: supportsESM ? "./test/jest-light-runner" : "jest-runner",

  collectCoverageFrom: [
    "packages/*/src/**/*.{js,mjs,ts}",
    "codemods/*/src/**/*.{js,mjs,ts}",
    "eslint/*/src/**/*.{js,mjs,ts}",
  ],
  // The eslint/* packages use ESLint v6, which has dropped support for Node v6.
  // TODO: Remove this process.version check in Babel 8.
  testRegex: `./(packages|codemods${
    Number(process.versions.node.split(".")[0]) < 10 ? "" : "|eslint"
  })/[^/]+/test/.+\\.m?js$`,
  testPathIgnorePatterns: [
    "/node_modules/",
    "/test/fixtures/",
    "/test/debug-fixtures/",
    "/babel-parser/test/expressions/",
    "/test/tmp/",
    "/test/__data__/",
    "/test/helpers/",
    "<rootDir>/test/warning\\.js",
    "<rootDir>/build/",
    "<rootDir>/.history/", // local directory for VSCode Extension - https://marketplace.visualstudio.com/items?itemName=xyz.local-history
    "_browser\\.js",
    ...(supportsESM ? importsSrc : []),
  ],
  testEnvironment: "node",
  setupFilesAfterEnv: ["<rootDir>/test/testSetupFile.js"],
  transformIgnorePatterns: [
    "/node_modules/",
    "<rootDir>/packages/babel-standalone/babel(\\.min)?\\.js",
    "/test/(fixtures|tmp|__data__)/",
    "<rootDir>/(packages|codemods|eslint)/[^/]+/lib/",
  ],
  coveragePathIgnorePatterns: [
    "/node_modules/",
    "<rootDir>/packages/babel-standalone/babel(\\.min)?\\.js",
    "/test/(fixtures|tmp|__data__)/",
  ],
  modulePathIgnorePatterns: [
    "/test/fixtures/",
    "/test/tmp/",
    "/test/__data__/",
    "<rootDir>/build/",
  ],
  resolver: supportsESM ? "./test/jestExportsMapResolver.cjs" : null,
  // We don't need module name mappers here as depedencies of workspace
  // package should be declared explicitly in the package.json
  // Yarn will generate correct file links so that Jest can resolve correctly
  moduleNameMapper: null,
};