[Bug]: jest.config.ts parsing broken on node 24 + CJS

[Marsup]

Version

30.0.0

Steps to reproduce

Apparently, typescript configuration file parsing is broken in jest 30 when used in a module that is still configured in CJS because it's now relying on node to do the parsing. Since node is only about type stripping, if you are still part of the unlucky crowd that hasn't managed to make the jump to ESM, you'll get this:

Error: Jest: Failed to parse the TypeScript config file ./jest.config.ts
  SyntaxError: Cannot use import statement outside a module

I traced it back to #15480.

My current workaround is to always have --no-experimental-strip-types set, but it's not ideal.

Expected behavior

I think it should only use node's parser if process.features.typescript is on, and the module is in ESM, but that last part seems tricky.

Actual behavior

It crashes.

Additional context

No response

Environment

System:
    OS: Linux 6.14 Ubuntu 25.04 25.04 (Plucky Puffin)
    CPU: (16) x64 Intel(R) Core(TM) i7-10875H CPU @ 2.30GHz
  Binaries:
    Node: 24.2.0
    npm: 11.3.0
    pnpm: 9.15.5
  npmPackages:
    jest: ^30.0.0 => 30.0.0

[mrazauskas]

Let’s ping @phryneas

[phryneas]

I'm gone for a few days but please feel free to give me another ping if I forgot to get back to this by the end of next week.

[phryneas]

@Marsup please take a look at #15694 - please also give feedback if renaming your jest.config.ts to jest.config.mts also solves the problem without any changes to Jest.

[Marsup]

@phryneas the message I get doesn't match the regexp: SyntaxError: Cannot use import statement outside a module.

[Marsup]

Oh, and about the mts change, jest doesn't seem to accept mts extensions.

[phryneas]

@Marsup sorry, I say your feedback on the Regex too late - which version of node are you using?

@cpojer we might need a follow-up-PR, could you please reopen this issue?

[mrazauskas]

By the way, it might be worth considering Node.js behaviour.

Recently I was trying to run a .ts file (using Node.js 24) in a project that did not specify the type field in package.json:

(node:76322) [MODULE_TYPELESS_PACKAGE_JSON] Warning: Module type of file:///***/index.ts is not specified and it doesn't parse as CommonJS.
Reparsing as ES module because module syntax was detected. This incurs a performance overhead.
To eliminate this warning, add "type": "module" to /***/package.json.

And when type: "commonjs" got specified, Node.js required .mts extension:

Failed to load the ES module: /***/index.ts. Make sure to set "type": "module" in the nearest package.json file or use the .mjs extension.
***
SyntaxError: Cannot use import statement outside a module
***

[Marsup]

@phryneas I was using node 24.2.0, just tested on 24.3.0, same thing

[phryneas]

@Marsup could you please give #15720 a try and report back over there?