MSW fails to recognize a registered handler about msw HOT 1 CLOSED

Hi, @stevenpollack.

The root cause of this problem is a failing request. In more detail, MSW tries to construct a Request (using global fetch API), and fails with this:

This is because JSDOM, once again, takes away your globals and polyfills AbortController, which is a global present API in both browser and Node.js. Because it's a polyfill, Node.js won't recognize it, and will throw right over here:

The issue is also mentioned in Undici: nodejs/undici#1910 (comment)

1. Undici does this: https://github.com/nodejs/undici/blob/07fe3609d266ddc2309c303d9d87c001bb534791/lib/fetch/request.js#L414
2. Then, Node.js does this: https://github.com/nodejs/node/blob/544cfc5ef151bca8d625fbccc581200a77b00bc0/lib/events.js#L943

Solution

The solution is to prevent JSDOM from polyfilling existing globals. Alas, this isn't something we can do on MSW's side. I highly recommend you check that Undici issue and search the JSDOM repo for any recommendations on how to solve this—it's a bug on their end.

from msw.