MSW leaves cypress component test runner in a loop

Describe the bug

Cypress 7 recently released an interesting feature called component test runner. It allows to mount a component and run it in isolation, rather than having to run the entire application. I was trying to use it with MSW (which would be awesome!), but for some reason, starting the service worker makes the test behave weirdly, becoming flaky, sometimes looping and causing trouble.

Environment

• msw: 0.28.2
• nodejs: 14.14.0
• npm: 6.4.8
• browser: Chromium opened by cypress

To Reproduce

Steps to reproduce the behavior:

before, check this repro: https://github.com/yannbf/msw-cypress-component-issue

1. yarn
2. yarn cy
3. Select Login.test.jsx
4. Check the comments in https://github.com/yannbf/msw-cypress-component-issue/blob/main/src/components/Login.test.jsx#L9. As soon as you remove the start of the service worker, the tests flow naturally. When you add them, there’s something weird that results in cypress runner looping.

Expected behavior

MSW should not impact cypress

Screenshots

[roryschadler]

I’m having the same problem, and none of the above workarounds have worked for me. I’d really love to be able to use MSW in my Cypress tests, is there any progress on this issue?

[lmiller1990]

Ok thanks @kettanaito and @the-ult. I’ll poke around Cypress a bit, it probably won’t be until next week though. I’m fairly sure something is getting muddled up in the routing for CT.

The CT specific routes are here https://github.com/cypress-io/cypress/blob/develop/packages/server/lib/routes-ct.ts The shared routes are https://github.com/cypress-io/cypress/blob/develop/packages/server/lib/routes.ts

Small files, so this should not be too hard to debug.