[Unit tests] ReferenceError: require is not defined in ES module scope

[Diego Sogari]

Hello there. I'm doing a build of binaryen as a dependency of an npm package. Running check.py fails because the test/unit/input/asyncify.js cannot be run by nodejs when the nearest parent directory which contains package.json is configured with "type": "module". The error message from executing it directly is:

<redacted>/binaryen/test/unit/input/asyncify.js:6
var fs = require('fs');
         ^

ReferenceError: require is not defined in ES module scope, you can use import instead
This file is being treated as an ES module because it has a '.js' file extension and '<redacted>/package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.
    at file:///<redacted>/binaryen/test/unit/input/asyncify.js:6:10
    at ModuleJob.run (node:internal/modules/esm/module_job:218:25)
    at async ModuleLoader.import (node:internal/modules/esm/loader:329:24)
    at async loadESM (node:internal/process/esm_loader:28:7)
    at async handleMainPromise (node:internal/modules/run_main:113:12)

The solution is either adding a package.json with an empty configuration ({}) to the test/unit/input directory or changing the script extension to .cjs.

[Alon Zakai]

Which node.js version are you using? I think I saw this before and it depends on the node version, but I don't remember if newer or older versions show the error.

[Diego Sogari]

I'm using v20.11.0

[Alon Zakai]

Thanks, I can't reproduce the issue though:

NODE=~/Downloads/node-v20.11.0-linux-x64/bin/node ./check.py unit

That runs all the unit tests with node 20.11, and they pass.

Which test specifically fails for you?

[Diego Sogari]

Just for clarity, in your test did you add a package.json file with {"type": "module"} in a parent folder?

[Alon Zakai]

No, I was trying to first see the error before seeing if that fixes it.

To make sure I verified there is no such file in the directory, nor any parent.

[Diego Sogari]

No, what I mean is, to reproduce this error, there should be package.json in a parent directory with type module (which is what my project is). Sorry for the misunderstanding.

I edited the original issue comment to be a little more precise about this fact.

[Alon Zakai]

I see, apologies for my confusion. That was probably obvious to someone that knows more JS, unlike me 😄

I can reproduce and see the proposed fix works. Opened #6245

[Diego Sogari]

No worries, I'm also a JS newcomer. 😄

Thanks for your quick feedback and resolution!