feat: add a global mocha variable

[CheadleCheadle]

PR Checklist

• Addresses an existing open issue: fixes 🚀 Feature: Add a global variable in tests indicating the test runner name and version #5084
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

Mocha now has the mochaVar (open to different name) property in the global scope, including its current name and version. This global property enables external testing utilities to statically identify both the version of Mocha in use and the specific testing framework being utilized.

[JoshuaKGoldberg]

Marking as draft pending triage of #5084. Thanks for sending it in the meantime! ❤️

[coveralls]

coverage: 94.343% (+0.008%) from 94.335%
when pulling 2bd1301 on CheadleCheadle:global-object
into f9e87d6 on mochajs:master.

[JoshuaKGoldberg]

Oop, I missed that #5084 was marked as accepting PRs. Un-drafting this 🚀

[JoshuaKGoldberg]

Looks very reasonable to me, thanks for the patience on it not being reviewed for a while! Just a couple small changes requested -really only one behavioral one- WDYT?

[JoshuaKGoldberg]

Unrelated permissions change, could you please revert?

[JoshuaKGoldberg]

This is fine for most JS environments, but some sandboxed ones disallow changing globalThis and might even throw. https://github.com/endojs/endo exists today; https://github.com/tc39/proposal-shadowrealm will hopefully exist eventually.

Let's wrap this in a try/catch the same way Error.stackTraceLimit = Infinity; is wrapped:

mocha/lib/cli/cli.js

Lines 43 to 47 in 3f13bbc

	try {
	Error.stackTraceLimit = Infinity; // configurable via --stack-trace-limit?
	} catch (err) {
	debug('unable to set Error.stackTraceLimit = Infinity', err);
	}