--loader=testdouble causes ERR_UNKNOWN_FILE_EXTENSION

[didiercolens]

Description

If I use the --loader=testdouble with mocha, I get an ERR_UNKNOWN_FILE_EXTENSION as described in nodejs/node#34049. I guess because mocha does not have an extension and testdouble tries to load it somehow?

Issue

Using any of:

• node --loader=testdouble ./node_modules/.bin/mocha
• NODE_OPTIONS='--loader=testdouble' ./node_modules/.bin/mocha
• NODE_OPTIONS='--loader=testdouble' npx mocha

yields the following error:

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension "" for /app/node_modules/mocha/bin/mocha
    at new NodeError (internal/errors.js:322:7)
    at defaultGetFormat (internal/modules/esm/get_format.js:71:15)
    at getFormat (file:///app/node_modules/quibble/lib/quibble.mjs:65:12)
    at Loader.getFormat (internal/modules/esm/loader.js:105:42)
    at Loader.getModuleJob (internal/modules/esm/loader.js:243:31)
    at async Loader.import (internal/modules/esm/loader.js:177:17)
    at async Object.loadESM (internal/process/esm_loader.js:68:5) {
  code: 'ERR_UNKNOWN_FILE_EXTENSION'
}

Environment

• node -v output: v14.18.2
• npm -v (or yarn --version) output: 6.14.15
• npm ls testdouble (or yarn list testdouble) version: testdouble@3.16.3

Also tested with:

• node -v output: v17.2.0
• npm -v (or yarn --version) output: 8.1.4
• npm ls testdouble (or yarn list testdouble) version: testdouble@3.16.3

Failing Test

• cd empty folder
• npm init
• npm install mocha testdouble -D
• node --loader=testdouble ./node_modules/.bin/mocha

[searls]

Hey @giltayar is this related to your work? (I see "loader" and think of you)

[giltayar]

Yup, you linked to the right issue. This is a problem in Node.js, and not in testdouble. I've never had a problem because I use mocha --loader=testdouble , and that works well.

I actually did have a problem, when working on testdouble itself, because the tests there run with another testrunner that is run with just node and has no extension, and so I created a "proxy" file with a .js which does a require("./node_modules/.bin/mocha") and ran that instead of mocha: https://github.com/testdouble/quibble/blob/dd2b78f21d0aac3ccaada6f8971cf283dbd25f79/package.json#L17