2028220 - devtools/client/debugger/test/mochitest/browser_dbg-event-breakpoints.js intermittently fails with stencil navigation enabled

Status: RESOLVED FIXED

(DevTools :: Debugger, task)

Description

[Tooru Fujisawa [:arai]]

derived from bug 2027803 comment #4.

The following assertion intermittently fails with the stencil navigation enabled, at least on linux asan, linux tsan on automation.
I can observe the issue on macOS debug build with test --verify.

https://searchfox.org/firefox-main/rev/9a3317a65545e83f4e32b94fdf1f6860342423ef/devtools/client/debugger/test/mochitest/browser_dbg-event-breakpoints.js#264

await assertPausedAtSourceAndLine(dbg, eventBreakpointsSource.id, 87);

The assertion sees the line being 82, which is the previous test's line, but

https://searchfox.org/firefox-main/rev/9a3317a65545e83f4e32b94fdf1f6860342423ef/devtools/client/debugger/test/mochitest/browser_dbg-event-breakpoints.js#251-267

info(`Check that breakpoint can be set on "beforeUnload" event`);
await toggleEventBreakpoint(dbg, "Load", "event.load.beforeunload");
let onReload = reload(dbg);
await waitForPaused(dbg);
await assertPausedAtSourceAndLine(dbg, eventBreakpointsSource.id, 82);
await resume(dbg);
await onReload;
await toggleEventBreakpoint(dbg, "Load", "event.load.beforeunload");

info(`Check that breakpoint can be set on "unload" event`);
await toggleEventBreakpoint(dbg, "Load", "event.load.unload");
onReload = reload(dbg);
await waitForPaused(dbg);
await assertPausedAtSourceAndLine(dbg, eventBreakpointsSource.id, 87);
await resume(dbg);
await onReload;
await toggleEventBreakpoint(dbg, "Load", "event.load.unload");

When I forcibly stop at the first assertion failure, the source view indeed stops at line 82, with the breakpoint being set to line 82,
and in the sidebar, both beforeunload and unload are checked.

https://searchfox.org/firefox-main/rev/9a3317a65545e83f4e32b94fdf1f6860342423ef/devtools/client/debugger/test/mochitest/shared-head.js#469-473

is(
  pauseLine,
  expectedLine,
  "Redux state for currently selected frame's line is correct"
);

Then, if I added logging for the checkbox state, in the failure case, the checkbox for the beforeunload is toggled from unchecked to checked, for both toggleEventBreakpoint calls, while the latter is supposed to toggle from checked to unchecked as a cleanup.

So, possibly either:

• the checkbox state doesn't persist for some reason
• the checkbox state hasn't been restored after reload at that point

Comment 1

[Tooru Fujisawa [:arai]]

With the following put before the 2nd toggleEventBreakpoint call, I observe that the checkbox's checked property becomes false to true at that point.

{
  const eventCheckbox = await getEventBreakpointCheckbox(
    dbg, "Load", "event.load.beforeunload"
  );
  dump(`@@@@ checked=${eventCheckbox.checked}\n`);
  await waitFor(() => {
    dump(`@@@@ checked=${eventCheckbox.checked}\n`);
    return eventCheckbox.checked == true;
  });
  dump(`@@@@ checked=${eventCheckbox.checked}\n`);
}

It means the onReload promise doesn't wait for the breakpoint state restoration, which would mean that the breakpoint state is restored after the waitForSources's condition.

https://searchfox.org/firefox-main/rev/9a3317a65545e83f4e32b94fdf1f6860342423ef/devtools/client/debugger/test/mochitest/shared-head.js#1029-1032

async function reload(dbg, ...sources) {
  await reloadSelectedTab();
  return waitForSources(dbg, ...sources);
}

Anyway, the testcase (and possibly all others that uses the similar structure) should wait for the breakpoint state restoration before processing to the "uncheck" part.

Comment 2

[Tooru Fujisawa [:arai]]

Attachment: Bug 2028220 - Wait for the breakpoint checkbox state to be restored after reloading the page. r?#devtools-reviewers!

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/225686f76b2e
https://hg.mozilla.org/integration/autoland/rev/855e138a4680
Wait for the breakpoint checkbox state to be restored after reloading the page. r=devtools-reviewers,nchevobbe

Comment 4

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/855e138a4680