Changes to handlers for node is not being picked up by live reload

Prerequisites

• I confirm my issue is not in the opened issues
• I confirm the Frequently Asked Questions didn’t contain the answer to my issue

Environment check

• I’m using the latest msw version
• I’m using Node.js version 14 or higher

Node.js version

v14.18.2

Reproduction repository

https://github.com/vercel/next.js/tree/canary/examples/with-msw

Reproduction steps

• Run yarn dev
• Makes changes to handler for https://my.backend/book
• Refresh the page
• Changes made to handler is not being reflected

Current behavior

In msw@0.41.1, this version, changes made to handler was being reflected with live reload. After this version, this does not work anymore. Looks like a regression in versions after this

Expected behavior

Changes made to handler should be reflected without having to stop and start the server like in 0.41.1 version

[vietanhtran16]

Hey @kettanaito, I have created a repo that reproduce that live reload worked with msw@0.41.1 for handlers on server side process of NextJs. That is why I think it is a regression since it used to work. Could we reopen this issue please?

Steps to reproduce:

• Checkout the above branch on my fork

• cd examples/with-msw/

• yarn install

• yarn dev

• Trying changing mock response for https://my.backend/book (called in getServerSideProps) and https://my.backend/user (called when clicking on Load Reviews => request to API Routes => which calls https://my.backend/user)

• When you refresh the page, you should be able to see the updated mock response.

I have also attached a GIF as example

[chrisb2244]

@vietanhtran16 Not in a useful way - if you do that then you can see the functions being executed again by the hot-reload (e.g. if you put some console.log('Loading handlers') in initMocks or similar), but it doesn’t actually change the behaviour of the handlers (easily exhibited by putting a console.log('this is a test') in a handler, then changing the text logged - the hot-reload for Next occurs, the “Loading handlers” message appears, but triggering the MSW handler will still log the previous text (no idea why).

My previous hypothesis was some sort of unused worker vs active worker, but seems like kettanaito said that wasn’t possible, and I was unable in the time since then to get any top running in the same instance as my processes (Docker… 😕 ). I might try with a local copy (not Docker container) and see if it’s more readily debuggable, but I don’t currently have a new hypothesis as to what’s happening.