MSW error not visible to Axios

Describe the bug

(I’m not sure if this is an issue in axios or in MSW - feel free to redirect me if needed)

When using fetch to do a request to a non-existing MSW resource it throws a helpful MSW error. However this error is not visible when using axios (which just throws a Network error), which can cause a lot of time debugging in the wrong direction.

Environment

• msw: 0.26.0
• nodejs: 12.20.1
• npm: 6.14.10 (but not used)

Please also provide your browser version.

n/a

To Reproduce

Steps to reproduce the behavior:

1. git clone https://github.com/JCB-K/msw-axios-testcase
2. cd msw-axios-testcase
3. yarn
4. yarn test

Expected behavior

All tests should pass.

Screenshots

Axios or MSW?

Like I mentioned above, I’m unsure where the issue lies. Normally I would say axios since that is doing the request and MSW is just the server which should expose a network error. But this is a bit of a different kind of error since it happens in the same environment, and is probably caught in a different way?

[kettanaito]

I see this as yet another reason to tackle #539 as a console.error instead of an exception. For posterity:

• Exceptions in a request cycle are treated differently depending on a request client (fetch propagates, axios gracefully handlers).
• Forwarding a suggestion text to stderr results in a suggestion being printed while the original client request error thrown as well (given hitting a non-existing endpoint).

[JCB-K]

Nice! I think that https://github.com/mswjs/msw/issues/539 covers my use case. I don’t necessarily need my client-side code to see the error MSW produces (I wouldn’t see it if I requested a “real” server either), I just would want that that error to be visible when running tests since it would be a helpful nudge in the right direction.

When I tested that PR in your repository I got both fetch and axios tests failing. That’s because an unhandled request doesn’t throw an exception, so it never halts the native fetch/axios execution.

What node version are you running? It passes for me on both Node 12 and and Node 14. EDIT: Sorry got it now - you tested the tests in my repo agains your PR. Yes I think it makes sense to have both: a failing request promise on the “client side” (which would also happen in real life), and a console.logged error on the “server” (MSW) side.

Fetch managing to propagate the MSW error is actually the odd one here (not Axios), considering that the server and the client shouldn’t be able to communicate outside regular request<->response.