Calling a custom protocol breaks request interception

Describe the bug

If a link to a custom protocol (i.e. mailto:) is triggered on a page, then the mock service worker stops intercepting requests.

Environment

• msw: 0.36.3
• chrome: 97.0.4692.71
• firefox: 95.0.2

To Reproduce

Steps to reproduce the behavior:

1. Go to: https://codesandbox.io/s/quirky-browser-yjijd
2. Click on the Start Polling button
3. Notice that the responses gets intercepted by the mock service worker
4. Click on anchor tag with the custom protocol mailto: href
5. Notice that the interceptions stops as the polling continues

Expected behavior

That the mock service worker continues to intercept the calls

[kettanaito]

I’ve just tested this sandbox in another browser without any mailing clients configured. Clicking on the anchor opens my mailing client in another browser, preserving the sandbox. The polling keeps going after this, as the page’s context wasn’t destroyed.

[kettanaito]

That’s a valid concern. Interacting with custom protocols must not interfere with the request interception, given the page’s context is preserved. I don’t think the protocol interaction is the issue, though. Resources that are not requested will not be handled by the worker, so clicking on mailto: or arbitrary-protocol: links doesn’t trigger the “fetch” even in the worker to cause any kind of trouble. Perhaps try looking into the surrounding parts of the mocking setup and your app logic that may cause the mocks to break? Maybe there are some exceptions going on that could stir the investigation into the right direction.

Going to check on that sponsor link now. ✌️

Huge thanks for sponsoring MSW! 🎉