Check that an element has not been (intermittently) displayed in page


I currently use CodeceptJS+Puppeteer to test websocket driven pages.
I have the following scenario to test :

  • First browser loaded a page with a form in it
  • Second browser loaded a page with some hidden elements in it (hidden text for example)
  • First browser sends a form

This parts of scenario works fine. Then :

  • I should check that in second browser an element is displayed shortly (then disappears)
  • Or check that there was no changes in loaded page at all or there was no changes on a specific element (a text was not displayed at all)

In other words I would like to test if submitted form in first browser changes something (an element, a class of an element…) temporarily in the page of the second browser (or not).
My main concern is about the element being displayed for a short time.

Thanks for your help.
Best regards,