[Bug]: jest-runner Class private methods are not enabled with version 29.0.0

[mihaelaLo]

Version

29.0.0

Steps to reproduce

jest --runInBand

Expected behavior

Tests should run without errors

Actual behavior

I receive the following error:

SyntaxError: /Users/myUser/Workspace/projectName/node_modules/jest-runner/build/index.js: Class private methods are not enabled.
  91 |   }
  92 |
> 93 |   async #createInBandTestRun(tests, watcher) {
     |   ^
  94 |     process.env.JEST_WORKER_ID = '1';
  95 |     const mutex = (0, _pLimit().default)(1);
  96 |     return tests.reduce(
    at File.buildCodeFrameError (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/core/lib/transformation/file/file.js:249:12)
    at NodePath.buildCodeFrameError (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/core/node_modules/@babel/traverse/lib/path/index.js:143:21)
    at verifyUsedFeatures (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/helper-create-class-features-plugin/lib/features.js:97:18)
    at PluginPass.Class (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/helper-create-class-features-plugin/lib/index.js:72:44)
    at newFn (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/core/node_modules/@babel/traverse/lib/visitors.js:177:21)
    at NodePath._call (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/core/node_modules/@babel/traverse/lib/path/context.js:53:20)
    at NodePath.call (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/core/node_modules/@babel/traverse/lib/path/context.js:40:17)
    at NodePath.visit (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/core/node_modules/@babel/traverse/lib/path/context.js:100:31)
    at TraversalContext.visitQueue (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/core/node_modules/@babel/traverse/lib/context.js:105:16)
    at TraversalContext.visitMultiple (/Users/mihaela.lorincz/Workspace/the-st-james-mobile-app/node_modules/@babel/core/node_modules/@babel/traverse/lib/context.js:74:17)

error Command failed with exit code 1.

Additional context

my jest config:

  "jest": {
    "verbose": true,
    "moduleNameMapper": {
      "^[./a-zA-Z0-9@$_-]+\\.(png|jpg)$": "<rootDir>/node_modules/react-native/jest/assetFileTransformer.js"
    },
    "modulePaths": [
      "<rootDir>/src/"
    ],
    "preset": "react-native",
    "setupFiles": [
      "./node_modules/react-native-gesture-handler/jestSetup.js",
      "./jest/setupTests.js"
    ],
    "testEnvironment": "node",
    "transform": {
      "^.+\\.js$": "babel-jest"
    },
    "transformIgnorePatterns": [
      "node_modules/(?!react-native|react-native-gesture-handler|react-navigation|@react-native-async-storage/async-storage|redux-persist|react-native-keychain|)/"
    ]
  }

I do not get this error for versions 28.1.3 and 26.6.3

Environment

System:
    OS: macOS 12.5.1
    CPU: (12) x64 Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
  Binaries:
    Node: 18.8.0 - /usr/local/bin/node
    Yarn: 1.22.17 - /usr/local/bin/yarn
    npm: 8.18.0 - /usr/local/bin/npm
  npmPackages:
    jest: 29.0.0 => 29.0.0

[SimenB]

Why are you transpiling jest-runner?

[mihaelaLo]

@SimenB I do not have jest-runner in my dependencies, it is installed by jest core library. I have a JS project

[SimenB]

It's babel that's complaining about the syntax, not Node itself. If you just do require('jest-runner') it'll work fine for you since the Node version supports it. So something in your setup is running Babel on Jest's modules.

Do you have a reproduction I can check out?

[mihaelaLo]

No, it is in my prod app, on a private repo. Is there any other info that might help you? Thanks for help

[SimenB]

Without a reproduction there's not much I can do. I'd take a look at your setupFiles, do any of them import jest-runner?

[tobua]

Ran into the same issue with React Native. Seems like metro-react-native-babel-preset is involved. Here is the most basic reproduction I could come up with:

{
  "scripts": {
    "test": "jest"
  },
  "dependencies": {
    "@babel/runtime": "^7.18.9",
    "babel-jest": "^29.0.1",
    "jest": "^29.0.1",
    "metro-react-native-babel-preset": "^0.72.1"
  },
  "jest": {
    "transformIgnorePatterns": []
  }
}

babel.config.json

{ "presets": ["module:metro-react-native-babel-preset"] }

test/basic.test.js

import double from "./double";

test("Doubles the number", () => {
  expect(double(2)).toBe(4);
});
// test/double.js
export default (value) => value * 2;

As a workaround ignoring the already mentioned jest-runner from being transpiled works around the issue:

"transformIgnorePatterns": [
  "jest-runner"
]

[SimenB]

Ah, nice 👍 that explains why our integration test doesn't fail: https://github.com/facebook/jest/blob/dde24c85698259d9ce887ede9646847d0fff9554/examples/react-native/jest.config.js#L7

Still, weird it triggers... I'll look into it next week 🙂

---

But yeah, don't transpile node_modules would be best 🙂

[tobua]

Right, transforming all node_modules is kind of a bad idea. The initial post is using a popular hack to ignore all node_modules except some that are published as ESM and therefore need to be transpiled as well.

Noticed that there is a / slash at the end which prevents jest-runner from being ignored for some reason.

"transformIgnorePatterns": [
  "node_modules/(?!react-native|any-react-native-esm-package)"
]

When that slash is removed jest-runner doesn't have to be listed explicitly anymore.

[SimenB]

Ah, that explains it (over-eager negation). Not sure there's anything for Jest to do? We target specific node versions - if other tooling has other syntax requirements that's not on Jest I think?

[tobua]

I was able to successfully upgrade a React Native project with the error described here. Definitely nothing for Jest to do here as node_modules generally shouldn't be transformed. Metro could add @babel/plugin-proposal-private-methods to metro-react-native-babel-preset but I don't think that's necessary for now.

Edit: Some React Native packages also have to be transpiled because they are published with flow type annotations.

[SimenB]

Agreed, thanks!

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