addEventListener for "message" not relayed from browser extension

Current behavior

When testing a page where a browser extension content script sends a message via window.postMessage and a page is listening via window.addEventListener("message", ...) Cypress does not pass on this message.

Desired behavior

Cypress should pass on these events.

Test code to reproduce

https://github.com/kasbah/cypress-add-event-listener-repro

git clone https://github.com/kasbah/cypress-add-event-listener-repro
cd cypress-add-event-listener-repro
npm ci
npm serve

npm run test

To confirm that a similar test passes using playwright you can do:

npm run test-pw

Cypress Version

10.1.0

Other

May be related to https://github.com/cypress-io/cypress/issues/1567

[lmiller1990]

Thanks for clarifying. I’ll try and take another look at this, sometime this week. It seems like there’s a few other blockers? I’m not sure I can prioritize this one right now, but I’m definitely interested in the general “testing extensions with Cypress” problem, so I’ll try and loop back around to this later this week. Let me know if you come up with anything in the meantime.

As for the original issue - I am not sure we have a bug or any obvious actionable work to be done in the Cypress code base? Should we leave this open (which would imply we have a bug to fix) or would you be happy to close it (but continue the discussion)?

[kasbah]

Hey, it is the right code base indeed. It can currently take 3 seconds to register with the page which is why you aren’t getting to the right page. You need to wait just over 3 seconds before clicking the button.

I realise that the way this extension currently works has some problems and is not the best way to achieve the desired behavior. This will be fixed in a re-write. It’s part of why I’d like to have some e2e tests for the extension: to help with the re-write.

Unfortunately, in addition to all the e2e frameworks that I’ve tried not being that well set up to test extensions yet, I’ve hit another road block: in interacting with the external site during tests (mouser.com) we sometimes get flagged as a bot and get blocked. puppeteer-extra-plugin-stealth seems to be the best low-effort way to try and avoid this, but that means I need to use puppeteer I guess. I might have to give up on the idea of using e2e testing for this.