[Bug]: Unable to import external module with webpackIgnore

[Dreamsorcerer]

Version

All versions

Steps to reproduce

In my code I have:

import(/* webpackIgnore: true */ js_module)

Expected behavior

Import the module how a browser would import the module, based on the presence of the webpackIgnore comment. i.e. Making a network request to the provided URL.

Actual behavior

It attempts to import a local module:

Cannot find module 'http://localhost:8080/admin/js' from 'src/App.js'

[MillerSvt]

What does webpack have to do with jest?

Node.js does not support https?: url scheme. It throws an error:

Error [ERR_UNSUPPORTED_ESM_URL_SCHEME]: Only URLs with a scheme in: file, data, and node are supported by the default ESM loader. Received protocol 'https:'

So, I think it is working as expected.

[Dreamsorcerer]

So, you're saying that the code is basically untestable because Node doesn't support the import() function like a browser does?

[Dreamsorcerer]

Found an article suggesting I may be able to hack it in:
https://dev.to/mxfellner/dynamic-import-with-http-urls-in-node-js-7og

I'll experiment with that then.

[MillerSvt]

Have you tried jest.mock function for that import?

[Dreamsorcerer]

I need the import to actually work, so I'll still need to provide some kind of implementation of the import() logic, right?

[MillerSvt]

I think that unit test should never depend on http resources. It significantly increase execution time, and make tests flaky (depending on your network conditions). So the best choise is mock any external modules with some stub implementations.

[Dreamsorcerer]

I have a complex application, which I'm sure is very unusual for a node/react app. I need to verify that the code in that module works with the app, and I need to verify that it gets loaded dynamically at runtime. It is being served by the (Python) backend web application, so this is really all technically integration testing, not unit tests. Network conditions are not relevant, it's all local and part of the larger test.

[github-actions]

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