Jest encountered an unexpected token with react-native

Question

So I'm trying to write tests on my React Native app with Jest and TypeScript. While using old babel version everything worked fine, but because of some project problems we had to upgrade babel to 7.0.0. After that I couldn't make it work. Any help is appreciated

Jest encountered an unexpected token This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript. By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".

/app/node_modules/react-native-calendar-events/index.ios.js:3 import { NativeModules } from 'react-native';

SyntaxError: Unexpected token import

package.json:

"dependencies": {
    "react": "16.4.1",
    "react-native": "0.56.0",
    "react-native-calendar-events": "^1.6.1",
    "react-redux": "^5.0.7",
    "react-router": "^4.3.1",
    "react-router-native": "^4.3.0",
    "react-router-redux": "5.0.0-alpha.9",
    "redux": "^4.0.0",
    "redux-api-middleware": "^2.3.0",
    "redux-form": "^7.4.2",
    "redux-thunk": "^2.3.0",
    "urijs": "^1.19.1"
  },
  "devDependencies": {
    "@babel/core": "^7.0.0",
    "@babel/preset-env": "^7.0.0",
    "@types/history": "^4.7.0",
    "@types/jest": "^23.3.1",
    "@types/react": "^16.4.13",
    "@types/react-native": "^0.56.17",
    "@types/react-router": "^4.0.30",
    "@types/react-router-native": "^4.2.3",
    "babel-core": "^7.0.0-bridge.0",
    "babel-jest": "^23.4.2",
    "babel-loader": "^8.0.2",
    "babel-preset-react-native": "^5.0.0",
    "jest": "^23.5.0",
    "react-native-typescript-transformer": "^1.2.10",
    "react-test-renderer": "^16.4.2",
    "ts-jest": "^23.1.4",
    "typescript": "^3.0.3"
},


"jest": {
    "preset": "react-native",
    "transform": {
      "^.+\\.ts?$": "ts-jest",
      "^.+\\.tsx?$": "ts-jest",
      "^.+\\.js$": "babel-jest"
    },
    "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.(jsx?|tsx?)?$",
    "moduleFileExtensions": [
      "ts",
      "tsx",
      "js",
      "jsx",
      "json",
      "node"
    ],
    "moduleNameMapper": {
      "^.+\\.(css|less|scss)$": "identity-obj-proxy"
    },
    "transformIgnorePatterns": [
      "/node_modules/(?!(react-native|my-project|react-native-button|react-native-calendar-events)/)"
    ]
  }

babelrc:

{
  "presets": ["react-native", ["@babel/preset-env", {"modules": "commonjs"}]],
  "env": {
    "test": {
      "presets": ["react-native", ["@babel/preset-env"]]
    }
  }
}

Answer 1

This is a config that worked for me:

jest.config.js

module.exports = {
  preset: 'react-native',
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
  moduleDirectories: ['./node_modules', 'src'],
  cacheDirectory: '.jest/cache',
  transformIgnorePatterns: [
    '<rootDir>/node_modules/(?!@react-native|react-native)',
  ],
  moduleNameMapper: {
    '^[./a-zA-Z0-9$_-]+\\.svg$': '<rootDir>/tests/SvgStub.js'
  },
  setupFiles: ['./node_modules/react-native-gesture-handler/jestSetup.js'],
  modulePathIgnorePatterns: ['<rootDir>/packages/'],
  watchPathIgnorePatterns: ['<rootDir>/node_modules'],
}

babel.config

{
   presets: ['module:metro-react-native-babel-preset'],
   plugins: [
        'react-native-reanimated/plugin'
   ]
};

package.json

  "dependencies": {
   
    "react-native": "0.69.6",
    "react-native-reanimated": "2.9.1",
   
  },
  "devDependencies": {
    "@babel/core": "^7.19.3",
    "@babel/register": "^7.18.9",
    "@babel/runtime": "^7.19.4",
    "@react-native-community/eslint-config": "^3.1.0",
    "@testing-library/react-native": "^7.1.0",
    "@types/i18n-js": "^3.8.3",
    "@types/jest": "^29.0.0",
    "@types/pubsub-js": "^1.8.1",
    "@types/react": "~18.0.0",
    "@types/react-dom": "17.0.14",
    "@types/react-native": "^0.69.6",
    "@types/react-test-renderer": "^18.0.0",
    "@types/redux-mock-store": "^1.0.2",
    "@types/redux-thunk": "^2.1.0",
    "@types/styled-components": "^5.1.26",
    "@types/styled-components-react-native": "^5.1.3",
    "@typescript-eslint/eslint-plugin": "^5.40.1",
    "@typescript-eslint/parser": "^5.40.1",
    "babel-jest": "29.2.2",
    "babel-plugin-transform-remove-console": "^6.9.4",
    "eslint": "^7.32.0",
    "eslint-config-prettier": "^8.5.0",
    "eslint-plugin-prettier": "^4.2.1",
    "jest": "^29.2.2",
    "jest-junit": "^14.0.1",
    "jetifier": "^1.6.5",
    "lint-staged": "^13.0.3",
    "metro-react-native-babel-preset": "^0.70.3",
    "prettier": "^2.7.1",
    "react-native-svg-transformer": "^1.0.0",
    "react-test-renderer": "18.0.0",
    "redux-mock-store": "^1.5.4",
    "ts-jest": "^29.0.3",
    "ts-mock-imports": "^1.3.8",
    "typescript": "^4.8.4"
  },

Sources: https://github.com/facebook/jest/issues/11591#issuecomment-899508417

Answer 2

Found the solution. In transform you should use react-native/jest/preprocessor.js instead of babel-jest.

"jest": {
    "preset": "react-native",
    "moduleDirectories": [
      "node_modules",
      "src"
    ],
    "transform": {
      "^.+\\.ts?$": "ts-jest",
      "^.+\\.tsx?$": "ts-jest",
      "^.+\\.js$": "<rootDir>/node_modules/react-native/jest/preprocessor.js" <--- over here
    },
    "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.(jsx?|tsx?)?$",
    "moduleFileExtensions": [
      "ts",
      "tsx",
      "js",
      "jsx",
      "json",
      "node"
    ],
    "moduleNameMapper": {
      "^.+\\.(css|less|scss)$": "identity-obj-proxy"
    },
    "transformIgnorePatterns": []
}