1878842 - [wdspec] Add BiDi fixture to wait for N events

Status: RESOLVED WONTFIX

(Remote Protocol :: WebDriver BiDi, task, P3)

Description

[Julian Descottes [:jdescottes] (PTO -> Jan 5th)]

Many BiDi wdspec tests locally build arrays of events, eg:

    events = []

    async def on_event(method, data):
        events.append(data)

    remove_listener = bidi_session.add_event_listener(CONTEXT_CREATED_EVENT, on_event)
    await subscribe_events([CONTEXT_CREATED_EVENT])

    await bidi_session.browsing_context.navigate(
        context=top_context["context"], url=test_page_multiple_frames, wait="complete"
    )

    wait = AsyncPoll(
        bidi_session, message="Didn't receive context created events for frames"
    )
    await wait.until(lambda _: len(events) >= 2)
    assert len(events) == 2

With a fixture to wait for several events we could reduce the boilerplate to something like

    await subscribe_events([CONTEXT_CREATED_EVENT])
    wait_for_events = wait_for_n_events(CONTEXT_CREATED_EVENT, 2)

    await bidi_session.browsing_context.navigate(
        context=top_context["context"], url=test_page_multiple_frames, wait="complete"
    )

    events = await wait_for_events()
    assert len(events) == 2

Comment 1

[Henrik Skupin [:whimboo][⌚️UTC+1]]

I assume we would still have to pass a minimum amount of events to wait for into wait_for_events(). Also do we need an escape hatch via a timeout in case we do not see the expected amount of events? Right now we don't have that and as such test modules would run into a timeout.

Comment 2

[Julian Descottes [:jdescottes] (PTO -> Jan 5th)]

Attachment: Bug 1878842 - [wdspec] Fix BiDiSession.add_event_listener to handle several listeners

Using await would blocks the loop forever, so we can never have more than one listener for the same event.

Comment 3

[Julian Descottes [:jdescottes] (PTO -> Jan 5th)]

Attachment: Bug 1878842 - [wdspec] Add fixture to wait for N bidi events

Comment 4

[Julian Descottes [:jdescottes] (PTO -> Jan 5th)]

Attachment: Bug 1878842 - [wdspec] Migrate context_created.py to use wait_for_n_events

Depends on D200803

Comment 5

[Julian Descottes [:jdescottes] (PTO -> Jan 5th)]

Attachment: Bug 1878842 - [wdspec] Reuse wait_for_n_events internally in wait_for_event

Depends on 200805

Comment 6

[Julian Descottes [:jdescottes] (PTO -> Jan 5th)]

The work and discussion will happen upstream https://github.com/web-platform-tests/wpt/issues/44702