Mocha excepting process.argv always contain strings

[SirAnthony]

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 node_modules/.bin/mocha --version(Local) and mocha --version(Global). We recommend that you not install Mocha globally.

Description

Running mocha by require it with overriden process.argv will fail if args is not strings. It is hacky way but it allow to use multiple different runners by the same wrapper script, and it worked for mocha2 and mocha4. In mocha 6.0.2 this ends with error.

Steps to Reproduce

const fs = require('fs');
const mocha_file = fs.realpathSync('./node_modules/mocha/bin/_mocha')
process.argv = [process.argv[0], mocha_file, '-t', 20000]
require(mocha_file)

Expected behavior: consume option of number type also

Actual behavior:

current master line

/home/anthony/node_modules/mocha/lib/cli/options.js:87
      const pair = arg.split('=');
                        ^

TypeError: arg.split is not a function
    at nodeArgs.reduce (/home/anthony/node_modules/mocha/lib/cli/options.js:87:25)
    at Array.reduce (<anonymous>)
    at parse (/home/anthony/node_modules/mocha/lib/cli/options.js:85:67)
    at loadOptions (/home/anthony/node_modules/mocha/lib/cli/options.js:288:14)
    at Object.exports.main (/home/anthony/node_modules/mocha/lib/cli/cli.js:62:18)
    at Object.<anonymous> (/home/anthony/node_modules/mocha/bin/_mocha:10:23)
    at Module._compile (internal/modules/cjs/loader.js:701:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
    at Module.load (internal/modules/cjs/loader.js:600:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
    at Function.Module._load (internal/modules/cjs/loader.js:531:3)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:22:18)
    at Object.<anonymous> (/home/anthony/test_mocha.js:5:1)
    at Module._compile (internal/modules/cjs/loader.js:701:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
    at Module.load (internal/modules/cjs/loader.js:600:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
    at Function.Module._load (internal/modules/cjs/loader.js:531:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:754:12)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)

But fixing it in-place (arg.toString().split('=')) will not work because of yargs-parser similar issue.

Reproduces how often: always

Versions

• The output of mocha --version and node node_modules/.bin/mocha --version: 6.0.2
• The output of node --version: v.10.15.3

Additional Information

[plroebuck]

const fs = require('fs');
const mocha_bin = fs.realpathSync('./node_modules/mocha/bin/_mocha');
argv = [process.argv[0], mocha_file, '-t', 20000];
process.argv = argv.map(arg => JSON.stringify(arg));
require(mocha_bin)

[plroebuck]

Node's process.argv has always been a string array.

If your approach worked before, it was by happy accident; it was never supported...
The modification to your script above should fix your problem though.