TypeError: Jest: a transform must export something.

[DarkLite1]

🐛 Bug Report

After upgrading from jest 23.6.3 to 27.0.1 and running our test suite we get the following error message:

TypeError: Jest: a transform must export something.

To Reproduce

1. Clone the GIT repo
2. Upgrade jest:

   name  range   from       to      url
>( ) jest  latest  26.6.3  ❯  27.0.1  https://jestjs.io/

3. Run yarn test

Expected behavior

No error message

Debug log:

# content of ts-jest.log :
{"context":{"allowJs":false,"logLevel":20,"namespace":"jest-preset","package":"ts-jest","version":"26.5.6"},"message":"creating jest presets not handling JavaScript files","sequence":1,"time":"2021-05-25T13:21:43.451Z"}
{"context":{"allowJs":false,"logLevel":20,"namespace":"jest-preset","package":"ts-jest","version":"26.5.6"},"message":"creating jest presets not handling JavaScript files","sequence":2,"time":"2021-05-25T13:21:43.474Z"}
{"context":{"logLevel":20,"namespace":"Importer","package":"ts-jest","version":"26.5.6"},"message":"creating Importer singleton","sequence":3,"time":"2021-05-25T13:21:45.906Z"}

envinfo

System:
    OS: Windows Server 2016
    Node version: 14.15.4

Npm packages:
    jest: 27.0.1
    ts-jest: 26.5.6
    typescript: 4.2.4

Related issue

[silverbucket]

Getting the same error. sockethub/sockethub#429

$ cat jest.config.js
module.exports = {
  preset: 'ts-jest',
  testEnvironment: 'node',
  coverageThreshold: {
    global: {
      branches: 75,
      functions: 80,
      lines: 90,
      statements: 90,
    },
  },
  coverageReporters: [
    'json',
    'lcov',
    'text',
    'clover',
  ]
};

Package versions:

    "@types/jest": "26.0.23",
    "jest": "27.0.1",
    "ts-jest": "26.5.6",

[ahnpnl]

duplicate #2611

[DarkLite1]

Thank you for the feedback. It might be a good idea to keep one of the issues open so it's easy to find. That's why I thought it wasn't an issue anymore as it was closed.

[covertbert]

So which is the issue that's actually tracking this as both this and the linked one are closed? I've just upgraded to 27.0.1 and I'm getting this error

[ahnpnl]

pls clear Jest cache and use ts-jest 27.0.0

[covertbert]

That worked, thank you!

[igauravsehrawat]

Thanks. Saved the day!

[Jeff-Tian]

Met the same issue with "jest": "^27.0.1" and fixed by revert to "jest": "^26.4.2",.

[ahnpnl]

You have to use ts-jest 27.0.1 and clear jest cache @Jeff-Tian

[PhiLhoSoft]

Also reverted, because I don't use ts-jest, but @angular-builders/jest. Will wait to switch to Angular 12 before updating this one.

[asohail-futu]

Still getting this issue even after clearing the jest cache and updating ts-jest to 27.0.1.
Is there any other step that needs to be done?

[ahnpnl]

You should clear Jest cache via jest —clearCache

[asohail-futu]

I used this: npx jest --clearCache
which showed this message after running: Cleared /private/var/folders/mr/pkt42jm120gbnm9lddwm_n9cl2tb8h/T/jest_alc100
That seemed to have cleared the cache

[asohail-futu]

I used this: npx jest --clearCache
which showed this message after running: Cleared /private/var/folders/mr/pkt42jm120gbnm9lddwm_n9cl2tb8h/T/jest_alc100
That seemed to have cleared the cache

adding to the previous comment – clearing the cache didn't solve the issue for me. I'm still getting the original error mentioned in this thread.

[ahnpnl]

how about remove node_modules and reinstall? I think Jest is reading ts-jest from another dependency not direct dependency.

Please make sure that there are no other dependencies using ts-jest 26, otherwise Jest will keep loading that version instead of your direct ts-jest 27 dep.

[asohail-futu]

btw, thank you so much for your quick replies and all your work with ts-jest!

I already tried doing a clean install of node_modules and upon your suggestion looked through the versions of ts-jest being used in package-lock – only v27 is being used.

[sauldeleon]

@asohail-futu check the version of jest you are using. In my case the issue was that I was using jest v26 with ts-jest v27. I was not installing jest directly, it was a dependency from Create React App. Maybe you are having the same issue!

[asohail-futu]

Thanks for the suggestion @sauldeleon but the issue still occurred while using jest v27 and no other dependency was using v26, as far as I could check. For now, I've reverted back to v26.

[sauldeleon]

@asohail-futu are you using react-scripts? in my case just check .lock file and see if any subdependant library is using jest 26. I had to use yarn resolutions feature to force react-scripts to use also jest 27.

I have also reverted to jest 26, but if you need jest 27 you can try that workarround

[Xaz16]

how about remove node_modules and reinstall? I think Jest is reading ts-jest from another dependency not direct dependency.

Please make sure that there are no other dependencies using ts-jest 26, otherwise Jest will keep loading that version instead of your direct ts-jest 27 dep.

I don't want to use jest 27 due to we have in issue with raised memory usage in this version (#2696). Does it mean that backward compatibility is broken?

[ahnpnl]

there is never a compatibility support before. Major version of ts-jest always follows Jest major version.

[Xaz16]

there is never a compatibility support before. Major version of ts-jest always follows Jest major version.

Ok, got it. It is hard to understand, because now I'm in situation when all pipelines is down, but ok.
When can we wait for fix of that one? #2696

[michaeleliot]

Not sure if it will help, but I had this issue because my version of jest globally differed from the version in the project I was working on. Running sudo npm i -g jest@latest resolved the issue for me.

[hansiemithun]

And this fix is leading to: TypeError: Cannot read property 'bind' of undefined. runtime.setGlobalsForRuntime is undefined now.

Reference: jestjs/jest#11720

[samuelneff]

Reverting from 27.x to 26.5.6 resolved the problem for me.

Clearing cache and re-installing node modules did not.

[cmcnicholas]

Reverting from 27.x to 26.5.6 resolved the problem for me.

Clearing cache and re-installing node modules did not.

Exactly the same here, clear cache, re-installing node_modules, another developer checking out on fresh machine, no cigar. Downgrading worked first time.

[karol-majewski]

Clearing cache & reinstalling did not help me, but upgrading jest-cli to ^27.2.1 did.

[whatwewant]

fixed by upgrading jest to ^27.2.1 for me

[zirkelc]

In my case I had jest and ts-jest both installed in 27.x.x, but an old version of react-scripts was referencing v26 which caused the issue: