wheresrhys/fetch-mock-jest

Doesn't seem to mock global by default

Closed this issue · 7 comments

jquense commented

Trying this out and i've found that jest is always resolving fetch-mock to the CJS server entry, and not the browser one, which results in the global fetch not being polyfilled. Is there a config i'm missing?

jquense commented

Oops spoke to soon, this doesn't work, because the browser field points to an mjs file, which jest can't handle

wheresrhys commented

Hey - first real user issue raised. Welcome 😄

Have you tried any of the approaches mentioned here jestjs/jest#4637. It does feel more like a jest issue to workaround than a problem with this library (or with fetch-mock either)

jquense commented

Yeah so i realized that i was complicating it by failing to correctly setup fetch-mock with a polyfill first, but yeah, this is ultimately probably a problem with jest not handling mjs files. That said, since this is specifically a jest extension, it probably makes more sense to require the cjs file directly here instead of fetch-mock and hoping Jest does the right thing?

here is ultimately the jest config that got this working:

 },
  "jest": {
    "testEnvironment": "jsdom",
    "moduleNameMapper": {
      "fetch-mock$": "<rootDir>/node_modules/fetch-mock/cjs/client.js"
    },
    "setupFiles": [
     "whatwg-fetch"
    ]
  },
  • 👍2
wheresrhys commented

Yeah, that's a fair point. I didn't pay much attention to which file was being required, but am surprised that Jest - being the hippest test runner around - doesn't play nice with .mjs

I'll need to restructure this repo to have different server.js and browser.js exports in that case. No time to do so tonight, but maybe later this week.

wheresrhys commented

@jquense I'd be grateful if you could try out v1.1.0-beta.2 to see if it works even when you remove the extra config you passed to jest

wheresrhys commented

Please try v1.2.0 of this library and reopen the issue if it's still broken