Context

The ticket has been rephrased.
The issue first appeared in PublicationWorkflowFunctionalTests#scheduledPublication, where we did a logout/login action.
A bit later, since a certain time, we see arbitrary failures on the very first login to AdminCentral (often in AssetsCoreFunctionalTests).

Possible culprits are:

• "Slower" ubuntu images on jenkins slaves
• "Issues" on the Vaadin side.

On the UI test, if the issue appears, typically a NoSuchElement or a similar excpetion is thrown.

Acceptance criteria

1. 1st Login on a UI-test works fine.
2. logout/login within a test (after 1st login) works fine
3. test-fkw has self-tests ensuring (1), (2)
4. the test-fwk provides an "API" which checks whether "vaadin is done".
5. During " UI-test init phase", the test-fwk ensures that "vaadin is done" / the UI hence ready to receive selenium commands

Developer note

The test-fwk already comes with (kind of) support for "vaadin is done" - see VaadinWebElementWrapper#vaadinIsDone.
Thus (4) prbly already is done. Though we make easier to access. (not sure if ...)

For (5) it would be helpful/desirable/likely-necessary that MGNLTEST-149 is resolved first. See pending PR . In consequence I add a dependency to that ticket.
If MGNLTEST-149 gets accepted/merged, the "vaadin is done" check for (5) most likely should be done within Selenium#initUiTest

Using the https://github.com/awaitility/awaitility might be helpful here.

Old description

info.magnolia.functionaltests.PublicationWorkflowFunctionalTests#scheduledPublication seems to fail with a high frequency. Attached a video recording showing the failure