Jest fails with "Unexpected token *" on import statement

Why does Jest fail with "Unexpected token *" on a simple import statement???

Error log:

Admin@Admin-PC MINGW32 /d/project (master)
$ npm run test

> MyApp@0.0.1 test D:\project
> jest

FAIL __tests__/App-test.tsx
  ? Test suite failed to run

    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".

    Here's what you can do:
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/en/configuration.html

    Details:

    D:\project\node_modules\react-navigation-tabs\src\navigators\createBottomTabNavigator.js:3
    import * as React from 'react';
           ^

    SyntaxError: Unexpected token *

      14 | // );
      15 |
    > 16 | export default createBottomTabNavigator({
         |                ^
      17 |   map: {
      18 |     screen: MapView,
      19 |     navigationOptions: {

      at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:471:17)
      at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:513:25)
      at Object.get createBottomTabNavigator [as createBottomTabNavigator] (node_modules/react-navigation-tabs/src/index.js:9:12)
      at Object.<anonymous> (src/app/main.view.tsx:16:16)

FAIL src/component/reinput/example/__tests__/index.ios.js (19.352s)
  ? Console

    console.error node_modules/react-native/Libraries/YellowBox/YellowBox.js:59
      Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: object. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

  ? renders correctly

    Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

      at invariant (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:55:15)
      at createFiberFromTypeAndProps (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:2054:11)
      at createFiberFromElement (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:2075:15)
      at reconcileSingleElement (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:4605:23)
      at reconcileChildFibers (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:4662:35)
      at reconcileChildren (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:6329:28)
      at updateHostRoot (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:6741:5)
      at beginWork (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:7566:14)
      at performUnitOfWork (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:11234:12)
      at workLoop (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:11266:24)

FAIL src/component/reinput/example/__tests__/index.android.js (19.365s)
  ? Console

    console.error node_modules/react-native/Libraries/YellowBox/YellowBox.js:59
      Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: object. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

  ? renders correctly

    Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

      at invariant (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:55:15)
      at createFiberFromTypeAndProps (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:2054:11)
      at createFiberFromElement (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:2075:15)
      at reconcileSingleElement (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:4605:23)
      at reconcileChildFibers (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:4662:35)
      at reconcileChildren (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:6329:28)
      at updateHostRoot (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:6741:5)
      at beginWork (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:7566:14)
      at performUnitOfWork (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:11234:12)
      at workLoop (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:11266:24)

Test Suites: 3 failed, 3 total
Tests:       2 failed, 2 total
Snapshots:   0 total
Time:        22.774s
Ran all test suites.
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! MyApp@0.0.1 test: `jest`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the MyApp@0.0.1 test script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\Admin\AppData\Roaming\Roaming\npm-cache\_logs\2019-04-22T11_52_36_984Z-debug.log

package.json file:

{
  "name": "MyApp",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node node_modules/react-native/local-cli/cli.js start",
    "test": "jest"
  },
  "dependencies": {
    "react": "16.8.3",
    "react-native": "0.59.4",
    "react-native-gesture-handler": "^1.1.0",
    "react-native-reanimated": "^1.0.1",
    "react-native-splash-screen": "^3.2.0",
    "react-navigation": "^3.8.1",
    "react-navigation-tabs": "^2.1.1"
  },
  "devDependencies": {
    "@babel/core": "^7.4.3",
    "@babel/runtime": "^7.4.3",
    "@types/jest": "^24.0.11",
    "@types/react": "^16.8.13",
    "@types/react-dom": "^16.8.4",
    "@types/react-native": "^0.57.46",
    "@types/react-test-renderer": "^16.8.1",
    "babel-jest": "^24.7.1",
    "jest": "^24.7.1",
    "metro-react-native-babel-preset": "^0.53.1",
    "react-test-renderer": "16.8.3",
    "typescript": "^3.4.3"
  },
  "jest": {
    "preset": "react-native"
  }
}

babel.config.js file:

module.exports = {
  presets: ['module:metro-react-native-babel-preset'],
};

jest.config.js file:

module.exports = {
  preset: 'react-native',
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
}

Note: I am using react-native type-script template, like react-native init MyApp --template typescript

Some react-native libraries ship uncompiled ES6 code.

ES6 code needs to be compiled before it can be run by Jest.

The Jest doc about Testing React Native Apps includes a section about compiling dependencies that don't ship pre-compiled code.

You will need to tell Jest to compile react-navigation-tabs by whitelisting it in the transformIgnorePatterns option in your Jest config.

Example:

Changing the jest.config.js file into something like below, fixed the issue mentioned in OP.

But the react-native-reanimated module (which requires native integration) needs further work, and we should "Mock" modules with such native requirements (as described in another post).

module.exports = {
  preset: 'react-native',
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
  transformIgnorePatterns: [
    "node_modules/(?!(react-native"
      + "|react-navigation-tabs"
      + "|react-native-splash-screen"
      + "|react-native-screens"
      + "|react-native-reanimated"
    + ")/)",
  ],
}

Note that the transformIgnorePatterns option (which is an array of Regular-Expressions) is originally meant to exclude files from being compiled, but using (?!(some-dir-name|another-name)) pattern, with the "(?!...)" negative look-ahead, we do tell Jest to exclude anything in node_modules directory, except the names that we did specify.

As it has been said, some modules needs to be transpiled, & some don't. Here is a regex I use that work in a lot of projects

  "jest": {
    "preset": "react-native",
    "transformIgnorePatterns": [
      "node_modules/(?!(jest-)?react-native|react-(native|universal|navigation)-(.*)|@react-native-community/(.*)|@react-navigation/(.*)|bs-platform|(@[a-zA-Z]+/)?(bs|reason|rescript)-(.*)+)"
    ]
  }

It's working for most common react native thing, & include also a specific package (here bs-platform) as an example, when isn't captured by previous patterns.

I had a similar issue on a React + Typescript app.

The first mistake I made was to define the jest.config.js as jest.config.ts

Running on Node v12.latest

Then the configuration that worked for me were the following:

// jest.config.js

module.exports = {
  preset: "ts-jest",
  testEnvironment: "node",
  roots: ["./src"],
  transform: { "\\.ts$": ["ts-jest"] },
  testRegex: "(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$",
  moduleFileExtensions: ["ts", "tsx", "js", "jsx", "json", "node"],
  globals: {
    "ts-jest": {
      tsConfig: {
        // allow js in typescript
        allowJs: true,
      },
    },
  },
};

// tsconfig.json
{
  "compilerOptions": {
    "target": "es5",
    "lib": ["dom", "dom.iterable", "esnext"],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "react",
    "baseUrl": "."
  },
  "include": ["src"],
  "exclude": ["node_modules", "**/*.spec.ts"]
}

// package.json
"devDependencies": {
    "@types/jest": "^26.0.5",
    "jest": "^26.1.0",
    "ts-jest": "^26.1.3"
}

Somewhere in your config file (.babelrc.js or package.json) you have to have "modules" under "presets" set to one of the "amd" | "umd" | "systemjs" | "commonjs" | "cjs" | "auto" | false.

referer this fragment from the documentation

something like this:

    "presets": [
  [
    "@babel/preset-env", {
      "targets": process.env.BABEL_TARGET === 'node' ? {
        "node": 'current'
      } : {
        "browsers": [ "last 2 versions" ]
      },
      "loose": true,
      "modules": 'commonjs'
    }
  ]
]

If you're using not only React Native but also Expo, I fixed the same issue but for Expo components by following the official guide, Testing with Jest. Specifically, install via package manager the jest preset jest-expo, and then update my package.json as they describe:

"jest": {
  "preset": "jest-expo",
  "transformIgnorePatterns": [
    "node_modules/(?!(jest-)?react-native|react-clone-referenced-element|@react-native-community|expo(nent)?|@expo(nent)?/.*|react-navigation|@react-navigation/.*|@unimodules/.*|unimodules|sentry-expo|native-base|@sentry/.*)"
  ]
}

I also needed to add to the end of the transformIgnorePatterns regexp string an exception for |.*font.* as the Expo Fonts were what were giving me trouble. Probably I could have made it a bit more specific, but I hate regex, and this worked so I left it there!

I am using react-native-web and the fix for my issue was to add the react-native-web preset to my jest.config.js:

module.exports = {
transform: {
  '^.+\\.tsx?$': 'ts-jest',
},
timers: 'fake',
testPathIgnorePatterns: [
  '<rootDir>/build/',
  '<rootDir>/node_modules/',
  '<rootDir>/rndemo/build/',
],
globals: {
  'ts-jest': {
    diagnostics: {
      warnOnly: true,
    },
  },
},
preset: 'react-native-web',
}

modifying babel.config.js to below worked for me. Also presets should come first and then all other configs.

    module.exports = {
       presets: [['@babel/preset-env',{targets: {node: 
         'current',},loose:true,},],],
    }