jest 24 with babel 6 and babel-jest 23

[jochakovsky]

🐛 Bug Report

Re-opening #8155

I've been unsuccessful at following the documentation for running Jest 24 with Babel 6. Specifically, I'm seeing this error:

Plugin/Preset files are not allowed to export objects, only functions.

If using Yarn, one possible workaround is adding "resolutions": {"babel-jest": "23.6.0"} to package.json.

To Reproduce

• Clone https://github.com/jochakovsky/Jest-24-Babel-6-preset-bug
• yarn install
• yarn run test

Expected behavior

Jest 24 should transpile test and src files using Babel 6

Link to repl or repo (highly encouraged)

https://github.com/jochakovsky/Jest-24-Babel-6-preset-bug

Run npx envinfo --preset jest

$ npx envinfo --preset jest
npx: installed 1 in 3.065s

  System:
    OS: macOS 10.14.4
    CPU: (8) x64 Intel(R) Core(TM) i7-6820HQ CPU @ 2.70GHz
  Binaries:
    Node: 8.11.2 - ~/.nvm/versions/node/v8.11.2/bin/node
    Yarn: 1.15.2 - /usr/local/bin/yarn
    npm: 6.4.1 - ~/.nvm/versions/node/v8.11.2/bin/npm
  npmPackages:
    jest: ^24.5.0 => 24.5.0 

[SimenB]

That's weird, I could have sworn I tested it... #5932 explicitly uses require.resolve instead of trying to resolve from a user's project.

@arcanis could we do something like

    try {
      babelJest = Resolver.findNodeModule('babel-jest', {basedir});
    } catch (e) {
      // ignored
    }
    if (!babelJest) {
      babelJest = require.resolve('babel-jest');
    }
    options.transform = {
      [DEFAULT_JS_PATTERN]: babelJest,
    };

instead of just require.resolve?

[SimenB]

@jochakovsky workaround is to add a jest.config.js file

module.exports = {
  transform: {
    '^.+\\.[jt]sx?$': require.resolve('babel-jest')
  }
};

[jochakovsky]

@SimenB Thank you, the workaround works for me!

[satsuya0114]

@jochakovsky workaround is to add a jest.config.js file

module.exports = {
  transform: {
    '^.+\\.[jt]sx?$': require.resolve('babel-jest')
  }
};

@SimenB can you add this to official document ?

I met this issue with babel@6 / jest@24 / babel-jest@23 at the same time
update this setting work fine finally !

[lin-credible]

package.json

  ......
  "devDependencies": {
    "@babel/core": "^7.4.5",
    "@babel/preset-env": "^7.4.5",
    "@babel/preset-typescript": "^7.3.3",
    "babel": "^6.23.0",
    "babel-core": "^6.26.3",
    "babel-eslint": "^10.0.1",
    "babel-jest": "^24.8.0",
    "babel-loader": "^7.1.4",
    "babel-plugin-react-transform": "^3.0.0",
    "babel-plugin-transform-es3-member-expression-literals": "^6.22.0",
    "babel-plugin-transform-es3-property-literals": "^6.22.0",
    "babel-polyfill": "^6.26.0",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-react": "^6.24.1",
    "babel-preset-stage-0": "^6.24.1",
    "babel-register": "^6.26.0",
    "babel-runtime": "^6.26.0",
    "happypack": "^5.0.0",
    "jest": "^24.8.0"
    ......

.babelrc

{
  "presets": ["react", "es2015", "stage-2"],
  "plugins": ["transform-es3-member-expression-literals", "transform-es3-property-literals"],
  "env": {
    "development": {
      "plugins": [
        [
          "react-transform",
          {
            "transforms": [
              {
                "transform": "react-transform-hmr",
                "imports": ["react"],
                "locals": ["module"]
              }
            ]
          }
        ]
      ]
    }
  }
}

Run yarn run test

yarn run v1.15.2
$ jest
 FAIL  src/__tests__/sum.test.js
  ● Test suite failed to run

    Plugin/Preset files are not allowed to export objects, only functions. In /Users/colintao/paas/code/tke-fe/node_modules/babel-preset-
react/lib/index.js

      at createDescriptor (node_modules/@babel/core/lib/config/config-descriptors.js:178:11)
      at items.map (node_modules/@babel/core/lib/config/config-descriptors.js:109:50)
          at Array.map (<anonymous>)
      at createDescriptors (node_modules/@babel/core/lib/config/config-descriptors.js:109:29)
      at createPresetDescriptors (node_modules/@babel/core/lib/config/config-descriptors.js:101:10)
      at presets (node_modules/@babel/core/lib/config/config-descriptors.js:47:19)
      at mergeChainOpts (node_modules/@babel/core/lib/config/config-chain.js:320:26)
      at node_modules/@babel/core/lib/config/config-chain.js:283:7
      at buildRootChain (node_modules/@babel/core/lib/config/config-chain.js:120:22)
      at loadPrivatePartialConfig (node_modules/@babel/core/lib/config/partial.js:85:55)

Run npx envinfo --preset jest

npx: installed 1 in 0.875s

  System:
    OS: macOS 10.14.5
    CPU: (8) x64 Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz
  Binaries:
    Node: 10.16.0 - /usr/local/bin/node
    Yarn: 1.15.2 - /usr/local/bin/yarn
    npm: 6.9.0 - /usr/local/bin/npm
  npmPackages:
    jest: ^24.8.0 => 24.8.0 

@jochakovsky @SimenB :help: the workaround doesn't work for me.

[nathanarritt]

@lin-credible The issue might be that you installed version 24 of babel-jest as opposed to version 23. I just installed version 23 and added the transform to my package.json file and it works as expected.
yarn add babel-jest@^23.6.0 -D
package.json
{ "jest": { "transform": { "^.+\\.[jt]sx?$": "<rootDir>/node_modules/babel-jest" } } }

[pkit]

No it does not.

require.resolve('babel-jest') resolves to 23.6.0 but without "workaround" I'm getting Plugin/Preset files are not allowed to export objects, only functions and with it I'm getting Requires Babel "^7.0.0-0", but was loaded with "6.26.3".
Like literally adding jest.config.js causes Requires Babel "^7.0.0-0" immediately

[ahmad-reza619]

Hi there, i'm using NPM here, and this issue still happens, but my error message is

unexpected token import

using jest@24, babel-jest@23, and babel 6

EDIT:

Solved the issue by downgrade jest to jest@23 👌

[StioDevolpper]

using jest 24 with babel 6 and babel-jest 23 with the workaround I'm getting this error Plugin / Preset files are not allowed to export objects only functions .. !

[mbdebian]

using jest 24 with babel 6 and babel-jest 23 with the workaround I'm getting this error Plugin / Preset files are not allowed to export objects only functions .. !

I got passed that error by adding the following at the end of my babelrc:

"test": [
        "jest"
    ]

This way, my whole babelrc file content looks like this:

{
    "presets": [
        "env",
        "react"
    ],
    "plugins": [
        "transform-class-properties",
        "transform-object-rest-spread"
    ],
    "test": [
        "jest"
    ]
}

But I can't get passed the following error when trying to write test cases for some React action generators:

 FAIL  src/tests/actions/expenses.test.js
  ● 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:

    /home/site/expensify-app/src/tests/actions/expenses.test.js:8
    import { addExpense, editExpense, removeExpense } from '../../actions/expenses'; // Test cases
           ^

    SyntaxError: Unexpected token {

      at Runtime._execModule (node_modules/jest-runtime/build/index.js:1179:56)

Apparently, jest doesn't understand ES6 import statement, and I've tried many different things, including downgrading jest, none of them worked.