1364276 - dom/test/mochitest/fetch/fetch_test_framework.js races service worker state change

Status: RESOLVED FIXED

(Core :: DOM: Service Workers, defect)

Description

[Ben Kelly [:bkelly, not reviewing]]

The dom/test/mochitest/fetch/fetch_test_framework.js has this dubious code:

      navigator.serviceWorker.register("worker_wrapper.js", {scope: "."})
        .then(function(registration) {
          if (registration.installing) {
            var done = false;
            registration.installing.onstatechange = function() {
              if (!done) {
                done = true;
                setupSW(registration);
              }
            };
          } else {
            setupSW(registration);
          }
        });

This waits for the installing service worker to progress to waiting, but not to actually activate.

The dom/cache version of this code does this instead:

  navigator.serviceWorker.ready.then(setupSW);
  navigator.serviceWorker.register("worker_wrapper.js", {scope: "."});

This avoids the race condition.

I need to fix this because my changes in bug 1293277 trigger this failure much more frequently.  It probably also explains a bunch of intermittent timeouts in these tests.

Comment 1

[Ben Kelly [:bkelly, not reviewing]]

Attachment: Wait for service worker to activate before proceeding in tests. r=asuth

Andrew, this just fixes the test framework to actually wait for the service worker to activate.  Its a pretty clear race that was already fixed in the dom/cache version of this framework code.

https://treeherder.mozilla.org/#/jobs?repo=try&revision=34a669b02d57fa679d06976348c78dea48566e36

Comment 2

[Ben Kelly [:bkelly, not reviewing]]

Comment on attachment 8867018 [details] [diff] [review]
Wait for service worker to activate before proceeding in tests. r=asuth

Hmm.  This causes other test failures in the same directory.

Comment 3

[Ben Kelly [:bkelly, not reviewing]]

Attachment: Wait for service worker to activate before proceeding in tests. r=asuth

So, we can't use the ready promise universally because the _sw_reroute tests have multiple service worker registrations with overlapping scopes.  Instead use a waitForState() helper throughout.

https://treeherder.mozilla.org/#/jobs?repo=try&revision=df5a83b973e01c07e1bc4ea4afd2878e05b57454

Comment 4

[Ben Kelly [:bkelly, not reviewing]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=ac32aed900c18ef7d9e15b3420053bf22442bf70

Comment 5

[Andrew Sutherland [:asuth] (he/him)]

Comment on attachment 8867426 [details] [diff] [review]
Wait for service worker to activate before proceeding in tests. r=asuth

Review of attachment 8867426 [details] [diff] [review]:
-----------------------------------------------------------------

There's some irony in the ready promise being great for everyone but SW implementers, and that its essential foot-gun-ness is not truly revealed until multiple tests interact.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/6237d34292cd
Wait for service worker to activate before proceeding in tests. r=asuth

Comment 7

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/6237d34292cd