not usable with msw ?

[0xCAFEADD1C7]

Hello there 👋

I'm discovering this lib, which seems great. I tried to integrate it in our codebase, however I have a strange behaviour, I'm using msw and my test don't pass anymore 🤔

It seems that the calls made with the wrapped fetched are not mocked anymore by msw. I made a simple repro here : https://github.com/0xCAFEADD1C7/fetch-retry-issue-repro

tried with node v20 and 22 and same issue. Also tried with the lib at version 6.0.0 and 5.0.6, same issue :/

Does it ring a bell to anyone ? Did I miss something obvious ?

[ptolemybarnes]

Hey @0xCAFEADD1C7 I had a quick look into this and found that if wrap fetch after the msw setup then it works:

it("should work with fetch-retry", async () => {
    const fetchWithRetry = withRetry(fetch, {
      retries: 1,
    });

    const result = await (
      await fetchWithRetry("https://foobarbazzz.com/user")
    ).json();

    expect(result).toEqual({
      success: true,
    });
  });

Also if you log out the fetch function received by fetch-retry:

For the failing test: [Function: fetch]
For the passing version: [AsyncFunction (anonymous)] { [Symbol(isPatchedModule)]: true }

So my guess is that the msw module patches/replaces the global fetch and because fetch-retry encloses over the original unpatched global fetch (unless you call it after the fact) then the interception doesn't work.

Interesting bug! I can't think of a solution right now but at least you have a workaround.

[ptolemybarnes]

Found another workaround... instead of passing fetch you pass a function that refers to global.fetch. That way it'll call the patched version:

const fetchWithRetry = withRetry((...args) => global.fetch(...args), {
  retries: 1,
});