🚀 Feature: Better error for --file option with non-existent file

[outsideris]

If specify non-existed file with --file option, mocha throw expection.

./bin/mocha --file non-existed
/Users/mocha/node_modules/yargs/yargs.js:1163
      else throw err
           ^

Error: Cannot find module '/Users/mocha/non-existed'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:582:15)
    at Function.Module._load (internal/modules/cjs/loader.js:508:25)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:22:18)
    at /Users/mocha/lib/mocha.js:309:36
    at Array.forEach (<anonymous>)
    at Mocha.loadFiles (/Users/mocha/lib/mocha.js:306:14)
    at Mocha.run (/Users/mocha/lib/mocha.js:784:10)
    at Object.exports.singleRun (/Users/mocha/lib/cli/run-helpers.js:108:16)
    at exports.runMocha (/Users/mocha/lib/cli/run-helpers.js:143:13)
    at Object.exports.handler.argv [as handler] (/Users/mocha/lib/cli/run.js:305:3)
    at Object.runCommand (/Users/mocha/node_modules/yargs/lib/command.js:242:26)
    at Object.parseArgs [as _parseArgs] (/Users/mocha/node_modules/yargs/yargs.js:1104:24)
    at Object.parse (/Users/mocha/node_modules/yargs/yargs.js:566:25)
    at Object.exports.main (/Users/mocha/lib/cli/cli.js:68:6)
    at Object.<anonymous> (/Users/mocha/bin/mocha:131:29)
    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)

It should be handled like --require.

./bin/mocha --require non-existed
mocha inspect [spec..]

Run tests with Mocha

Rules & Behavior
  --allow-uncaught           Allow uncaught errors to propagate        [boolean]

...

  --list-interfaces  List built-in user interfaces & exit              [boolean]
  --list-reporters   List built-in reporters & exit                    [boolean]

✖ ERROR: Cannot find module 'non-existed'

[JoshuaKGoldberg]

Here's what the current version of Mocha, 10.2.0, prints:

$ npx mocha --file wat
Warning: Cannot find any files matching pattern "test"

Error: Cannot find module '/Users/josh/repos/mocha-examples/packages/hello-world/wat'
Require stack:
- /Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/lib/nodejs/esm-utils.js
- /Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/lib/mocha.js
- /Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/lib/cli/one-and-dones.js
- /Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/lib/cli/options.js
- /Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/bin/mocha.js
    at Module._resolveFilename (node:internal/modules/cjs/loader:1144:15)
    at Module._load (node:internal/modules/cjs/loader:985:27)
    at Module.require (node:internal/modules/cjs/loader:1235:19)
    at require (node:internal/modules/helpers:176:18)
    at exports.requireOrImport (/Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/lib/nodejs/esm-utils.js:53:16)
    at async exports.loadFilesAsync (/Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/lib/nodejs/esm-utils.js:100:20)
    at async singleRun (/Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/lib/cli/run-helpers.js:125:3)
    at async exports.handler (/Users/josh/repos/mocha-examples/packages/hello-world/node_modules/mocha/lib/cli/run.js:370:5)

That first Warning: line is in yellow.

👍 that it'd be good to give a better error than "Error: Cannot find module '...'".

[khoaHyh]

Wasn't exactly sure if you wanted to keep the red Error so I have it in these two ways on my local branch. Lmk your preference and I can push it here: #5086.

[JoshuaKGoldberg]

Hmm, do we even need the call stacks in the first place? Here are what Jest and Vitest report:

$ jest wat
No tests found, exiting with code 1
Run with `--passWithNoTests` to exit with code 0
In ~/repo
  2 files checked.
  testMatch: **/__tests__/**/*.[jt]s?(x), **/?(*.)+(spec|test).[tj]s?(x) - 1 match
  testPathIgnorePatterns: /node_modules/ - 2 matches
  testRegex:  - 0 matches
Pattern: wat - 0 matches

 $ npx vitest wat

 DEV  v1.2.2 ~/repo

filter:  wat
include: **/*.{test,spec}.?(c|m)[jt]s?(x)
exclude:  **/node_modules/**, **/dist/**, **/cypress/**, **/.{idea,git,cache,output,temp}/**, **/{karma,rollup,webpack,vite,vitest,jest,ava,babel,nyc,cypress,tsup,build,eslint,prettier}.config.*
watch exclude:  **/node_modules/**, **/dist/**

No test files found, exiting with code 1

I think that kind of "relevant options" output would be much more useful than a big call stack. What do you think?

[khoaHyh]

Good point, I don't think we need the call stack and I'm not sure a diagnostic output like Jest's or Vitest applies here. Currently --file doesn't search under a glob and just searches at the supplied path so npx mocha --file file.spec.js would fail even if it exists under a glob specified in a config file.

I think the above clues in the user that they should specify a precise path, absolute or relative, which is how --file works atm.

[JoshuaKGoldberg]

Makes sense. If folks have a need for the extra fancy output they can always file a followup issue, I think. Thanks!

Accepting PRs! 🚀

[khoaHyh]

#5086 ready for review 👀

[JoshuaKGoldberg]

Awesome thanks! We're almost at the point where we can start reviewing PRs. This one is high up on the list given that it's a bugfix and doesn't touch too many things. Thanks!