TypeError: arg.split is not a function when passed a numerical argument

[nferch]

Prerequisites

• Checked that your issue hasn't already been filed by cross-referencing issues with the faq label
• Checked next-gen ES issues and syntax problems by using the same environment and/or transpiler configuration without Mocha to ensure it isn't just a feature that actually isn't supported in the environment in question or a bug in your code.
• '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, your usage of Mocha, or Mocha itself
• Ensured that there is no discrepancy between the locally and globally installed versions of Mocha. You can find them with: node_modules/.bin/mocha --version(Local) and mocha --version(Global). We recommend that you not install Mocha globally.

Description

With similar symptoms to #3861, Mocha fails when given a numerical argument:

>npx mocha 1234                                                                 
/Users/nf/.npm/_npx/508606763866ae01/node_modules/mocha/lib/cli/options.js:113
      const pair = arg.split('=');
                       ^

TypeError: arg.split is not a function
    at /Users/nf/.npm/_npx/508606763866ae01/node_modules/mocha/lib/cli/options.js:113:24
    at Array.reduce (<anonymous>)
    at parse (/Users/nf/.npm/_npx/508606763866ae01/node_modules/mocha/lib/cli/options.js:111:67)
    at loadOptions (/Users/nf/.npm/_npx/508606763866ae01/node_modules/mocha/lib/cli/options.js:246:10)
    at Object.<anonymous> (/Users/nf/.npm/_npx/508606763866ae01/node_modules/mocha/bin/mocha.js:27:14)
    at Module._compile (node:internal/modules/cjs/loader:1159:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1213:10)
    at Module.load (node:internal/modules/cjs/loader:1037:32)
    at Module._load (node:internal/modules/cjs/loader:878:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)

Node.js v18.12.1
[1]    79408 exit 1     npx mocha 1234

Expected behavior:
Mocha to proceed as expected, or to throw a more descriptive error message.

Actual behavior:
A crash and a stacktrace.

Reproduces how often:
100%

Versions

Mocha 10.2.0
Node v18.12.1
macOS Sonoma 14.0
zsh 5.9 (x86_64-apple-darwin23.0)

Additional Information

It can be expected that argv is a string array, but it appears that yargsParser.Arguments._ which is fed back into parse at

mocha/lib/cli/options.js

Line 246 in 48002bc

args = parse(args._, mocharc, args, rcConfig || {}, pkgConfig || {});

will contain numbers.

[Uzlopak]

Can you please provide a minimal viable code example, for example a repo to clone?

[nferch]

I'm able to repro this with https://github.com/mochajs/mocha-examples/tree/master/packages/typescript

>node_modules/.bin/mocha 12345
/Users/nf/src/mocha-examples/packages/typescript/node_modules/mocha/lib/cli/options.js:113
      const pair = arg.split('=');
                       ^

TypeError: arg.split is not a function
    at /Users/nf/src/mocha-examples/packages/typescript/node_modules/mocha/lib/cli/options.js:113:24
    at Array.reduce (<anonymous>)
    at parse (/Users/nf/src/mocha-examples/packages/typescript/node_modules/mocha/lib/cli/options.js:111:67)
    at loadOptions (/Users/nf/src/mocha-examples/packages/typescript/node_modules/mocha/lib/cli/options.js:246:10)
    at Object.<anonymous> (/Users/nf/src/mocha-examples/packages/typescript/node_modules/mocha/bin/mocha.js:27:14)
    at Module._compile (node:internal/modules/cjs/loader:1159:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1213:10)
    at Module.load (node:internal/modules/cjs/loader:1037:32)
    at Module._load (node:internal/modules/cjs/loader:878:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)

Node.js v18.12.1
[1]    68011 exit 1     node_modules/.bin/mocha 12345

[JoshuaKGoldberg]

Ha, I happened upon this accidentally while triaging an issue around --delay. npx mocha --delay 123 causes this. Accepting PRs!

[deauthe]

no solution yet?

[JoshuaKGoldberg]

@deauthe This repo is fully open source. It's staffed by volunteers such myself, not a private entity. If there is an update or solution it will be posted here.

If you're interested in this getting fixed, then the best next step would be to send a PR yourself. Since you seem interested in it I look forward to seeing your PR. 🙂

[deauthe]

@JoshuaKGoldberg Thank you for your response! I appreciate the work and effort that goes into maintaining mocha. My earlier message wasn’t intended to come across as rude, and I apologize if it seemed that way.

I value the work of volunteers like you, and I’ll take a closer look to see if I can contribute a PR to help address this issue.

[Dinika]

@deauthe @JoshuaKGoldberg I stumbled onto this issue too and would like to look into fixing it. If a PR is not already in the works, is it okay if I start working on this issue?

[JoshuaKGoldberg]

We don't have any kind of issue claiming system, as folks often end up not having time for things they'd wanted to do.

[Dinika]

Thanks for the go-ahead @JoshuaKGoldberg. I've opened a PR for this issue.