As David mentioned to me this event seems to block our testing capabilities for Gutenberg tests, and that I should have a look at it. I will have a look first how Chrome's behavior is, and then get it implemented for the remote agent.

This test indicates that those event's aren't only fired for Page related events but also for other domains like Network, which in this case is for networkIdle events.

Otherwise it needs to be fired for each top-level page lifecycle event like navigation, load, paint, etc... A list of important events where this event needs to be emited. Those events are:

    [0] : DOMContentLoaded
    [1] : firstContentfulPaint
    [2] : firstMeaningfulPaint
    [3] : firstMeaningfulPaintCandidate
    [4] : firstPaint
    [5] : init
    [6] : load
    [7] : networkAlmostIdle
    [8] : networkIdle

With the patch on this bug I will get this implemented for any event we currently support. For others a follow-up bug needs to be filed.

(In reply to Henrik Skupin (:whimboo) [⌚️UTC+2] from comment #1)

[1] : firstContentfulPaint
[2] : firstMeaningfulPaint
[3] : firstMeaningfulPaintCandidate
[4] : firstPaint

These events are all performance related. And none of them are blocking the Gutenberg test suite.

[7] : networkAlmostIdle
[8] : networkIdle

Both are related to the Network domain which we haven't implemented yet beside some individual methods and events. So they will have to be done at a later time.

[0] : DOMContentLoaded
[5] : init
[6] : load

Those are the additions which I will cover on this bug.

https://treeherder.mozilla.org/#/jobs?repo=try&revision=7f67fe3459cb5f8af4f2c5ca82f1f23a0fc53136

Looking at logs from a simple Puppeteer script, I also see a commit lifecycle event after {"method":"Target.createTarget","params":{"url":"about:blank"},"id":2} and Page.enable.

commit precedes DOMContentLoaded. Is it a Blinkism?

See:

• https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/inspector/inspector_page_agent.cc?type=cs&q=lifecycleevent&sq=package:chromium&g=0&l=592
• https://github.com/GoogleChrome/puppeteer/blob/d17708ba1fc8411941bfd07f633aaf2fb5cb671e/lib/LifecycleWatcher.js#L156

Here's a log in case it's useful. You can test your patch with this example, as well.

Depends on D53826

(In reply to Maja Frydrychowicz :maja_zf (UTC-4) (maja@mozilla.com) from comment #4)

Looking at logs from a simple Puppeteer script, I also see a commit lifecycle event after {"method":"Target.createTarget","params":{"url":"about:blank"},"id":2} and Page.enable.

commit precedes DOMContentLoaded. Is it a Blinkism?

As it looks like the commit lifecycle event is only emitted when Page.setLifecycleEventsEnabled is set to true. As it would be a commit for that change, and all the navigation lifecycle events will follow. As discussed with Maja we can follow-up on that, and she filed bug 1597762.

https://hg.mozilla.org/mozilla-central/rev/7da18cae2e37