🐛 Bug: Mocha stops testing when any test file has syntax error

[DmitryMakhnev]

Bug Report Checklist

• I have read and agree to Mocha's Code of Conduct and Contributing Guidelines
• I have searched for related issues and issues with the faq label, but none matched my issue.
• I have 'smoke tested' the code to be tested by running it outside the real test suite to get a better sense of whether the problem is in the code under test, my usage of Mocha, or Mocha itself.
• I want to provide a PR to resolve this

Expected

Have a failed test message for the file with syntax error, have reporter calls for the file with error, have dysplaying of other tests like in Node.js test runner (example.zip)

Actual

After call in termical I see only message
Exception during run: SyntaxError... and with Process finished with exit code 1.
Example mocha-for-files-and-file-with-syntax-error.zip

Minimal, Reproducible Example

Example mocha-for-files-and-file-with-syntax-error.zip

1. Download the example
2. Install dependencies: run npm i in terminal
3. Run tests: run npm run test:files in terminal
4. See result.

Versions

mocha version: 11.0.1
Node.js version: 22.3.0 (same for: 20.15.1, 18.17.1, 23.6.0)
macOS: 14.7 (23H124)
MacBook Pro 16-inch, 2021, Apple M1 Max
Terminal: iTerm2 Build 3.5.7, WebStorm 2025.1 EAP

Additional Info

No response

[JoshuaKGoldberg]

ACK on the reproduction. This is what I get locally:

$ npx mocha "tests/"

 Exception during run: SyntaxError[ @/Users/josh/repos/mocha-for-files-and-file-with-syntax-error/tests/sample.test.js ]: Unexpected token '.'
    at compileSourceTextModule (node:internal/modules/esm/utils:337:16)
    at ModuleLoader.moduleStrategy (node:internal/modules/esm/translators:164:18)
    at callTranslator (node:internal/modules/esm/loader:439:14)
    at ModuleLoader.moduleProvider (node:internal/modules/esm/loader:445:30)
    at async ModuleJob._link (node:internal/modules/esm/module_job:106:19)

Trying out other test runners:

• Jest: still runs valid test files
• Vitest: still runs valid test files

So, I think this is a reasonable request for Mocha. Multiple other mainstream test runners already have this feature. 👍 from me. cc @mochajs/maintenance-crew

Btw, a request: please don't post reproductions in .zip folders. The reproduction itself was very clear and useful (thank you!) but it's inconvenient -especially on mobile-, doesn't show up in searches, and is risky for us as maintainers opening arbitrary compressed files online. Something like a GitHub repository, GitHub Gist, or Stackblitz container would be helpful. For reference I personally keep a repository on GitHub with a branch per repro: https://github.com/JoshuaKGoldberg/repros. Thanks! 🙏

[voxpelli]

Feels loosely related to both #4947 and #4392

Like in #4947 and anything else that touches upon test isolation or that introduces new cases that needs to be handled by reporters or such I'm a bit weary. If someone comes up with an elegant simple way of fixing this, then I'm 👍, but if it requires fundamental changes or lots of added complexity, then I'm 👎 .

I agree that the behavior would be nice, but I'm not sure the cost of the changes needed for Mocha would merit the gains. I think this may fall under the #5027 of us trying to take it slow on any big changes.