[voxpelli]

Removes these from errors.js:

• warn() is no longer used anywhere and not publicly exported
• createInvalidPluginError() is no longer used anywhere, isn't publicly exported had to be explicitly imported from the specific file, has been deprecated since implementation of global setup/teardown; closes #4308 #4360, for 6 years now and has no public usage across GitHub
• deprecate() was only used by createInvalidPluginError() and not publicly exported
• emitWarning() was only used by warn() and deprecate() and contained an unnecessary polyfill for process.emitWarning, a function that has existed since Node 6.0.0 with us now requiring at least Node 20.19.0 - and it wasn't publicly exported.

This change simplifies the codebase by eliminating unused functions and their tests as well as their redundant polyfills.

PR Checklist

• Addresses an existing open issue: 📌 Mocha 12 Release Plan #5357
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Applicable issues

• This change is part of the Mocha 12 Release Plan: 📌 Mocha 12 Release Plan #5357
• It does not introduce breaking changes, as it only removes unused code.

[Copilot]

Pull request overview

This PR removes a legacy process.emitWarning polyfill in lib/errors.js, intending to rely solely on the native Node.js implementation now that Mocha’s minimum supported Node version is ^20.19.0 || >=22.12.0.

Changes:

• Remove the emitWarning polyfill wrapper from lib/errors.js and call process.emitWarning directly from deprecate() and warn().
• Simplify unit tests by always stubbing process.emitWarning in test/unit/errors.spec.js.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
lib/errors.js	Removes the emitWarning wrapper and calls process.emitWarning directly for warnings/deprecations.
test/unit/errors.spec.js	Simplifies setup/teardown around process.emitWarning stubbing in deprecate/warn tests.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.56%. Comparing base (1b3d604) to head (d42cb24).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5835   +/-   ##
=======================================
  Coverage   88.55%   88.56%           
=======================================
  Files          65       65           
  Lines        4659     4643   -16     
  Branches      978      974    -4     
=======================================
- Hits         4126     4112   -14     
+ Misses        533      531    -2     

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

test/unit/suite.spec.js:533

• The removed errors.deprecate stub means the errors import at the top of this file is now unused (only appears in the require). With ESLint js/recommended, this will trigger a no-unused-vars failure; please remove the unused errors import.

    describe("constructor", function () {
      /* eslint no-new: off */
      it("should throw an error if the title isn't a string", function () {
        expect(function () {
          new Suite(undefined, "root");

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[JoshuaKGoldberg]

LGTM, with the caveat that removing createInvalidPluginError is actually a breaking change and this PR should be rephrased as such.

Can I suggest manually writing the PR description?

[voxpelli]

@JoshuaKGoldberg I did manually write the majority of the final PR description.

As far as I can see the createInvalidPluginError is not a public API? So it shouldn't be a breaking change to remove it?

[JoshuaKGoldberg]

As far as I can see the createInvalidPluginError is not a public API? So it shouldn't be a breaking change to remove it?

#5835 (comment)

[mark-wiemer]

@JoshuaKGoldberg I'm good to merge this into v12 if you are now that we've updated #5357. One of the callouts is explicitly "removing long-deprecated options" :)

[mark-wiemer]

I will fix the formatting issue separately

[mark-wiemer]

@JoshuaKGoldberg you OK to merge this into v12?

[mark-wiemer]

For the record I did review the actual code :)

[JoshuaKGoldberg]

At this point I don't feel strongly. If you guys are ok with breaking the letter of the law to go with this interpretation of the spirit, I won't stand in the way. ✅

[mark-wiemer]

#5357 says "Mocha 12 will be used to ... Remove long-deprecated options and any other known dead code", I think this counts :)