1715653 - browser_modal_print.js perma-fails on Linux when run locally

Status: NEW

(Toolkit :: Printing, defect)

Description

[Daniel Holbert [:dholbert]]

browser_modal_print.js fails 100% of the time when run locally on my system, possibly because a print preview window is left open in one subtest, which trips up a later subtest (as far as I can tell, from adding some logging).

I'll post a logging patch and the results of the logs, and then I'm wondering if maybe Emma, Sam, or Mark can tell or figure out what's going on.

(I have a hunch that this is why this test was initially annotated as failing on fission in bug 1713912 -- it probably failed in someone's local fission-enabled testrun, and they assumed it was a fission-dependent failure, though it doesn't seem to repro on our treeherder testruns and doesn't seem to actually be fission-depdendent, AFAICT.)

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: diagnostic patch that I'm using to get more information about the failure

Comment 2

[Daniel Holbert [:dholbert]]

Attachment: snippet of log, showing exception being thrown in testPrintMultiple

If I'm understanding my log correctly, I think `testPrintMultiple` is the test that's failing here.

```

Comment 3

[Daniel Holbert [:dholbert]]

Attachment: log of local test run with my diagnostic patch applied

Comment 4

[Daniel Holbert [:dholbert]]

Here's a snippet of the test run, with the exception that I think is causing the problem here (though I'm not entirely sure):

 0:12.47 INFO Entering test bound testPrintMultiple
[...]
 0:13.65 PASS There is one print dialog - 
 0:13.66 PASS The dialog is visible - 
 0:13.66 PASS The URL of the browser is the one we expect - 
 0:13.66 GECKO(3580) console.log: ***DHOLBERT _openTabModalPrint: calling getPreviewBrowser
 0:13.66 GECKO(3580) console.log: ***DHOLBERT getPreviewBrowser: Entering function
 0:13.66 GECKO(3580) console.log: ***DHOLBERT getPreviewBrowser: browser is non-null! returning it.
 0:13.66 GECKO(3580) console.log: ***DHOLBERT _openTabModalPrint: rejecting in previewBrowser case
 0:13.66 INFO Console message: [JavaScript Error: "undefined" {file: "chrome://global/content/printUtils.js" line: 377}]
startPrintWindow/<@chrome://global/content/printUtils.js:377:12

 0:13.68 GECKO(3580) [Parent 3580, Main Thread] WARNING: 'nsContentUtils::GetCommonBrowserParentAncestor( remote, oldRemote) != remote', file /scratch/work/builds/mozilla-central/mozilla/dom/events/EventStateManager.cpp:1400
 0:13.68 INFO Console message: [JavaScript Error: "undefined" {file: "chrome://global/content/printUtils.js" line: 377}]
startPrintWindow/<@chrome://global/content/printUtils.js:377:12

The eventual summary of the failure is:

Overall Summary
===============

mochitest-browser
~~~~~~~~~~~~~~~~~
Ran 55 checks (54 subtests, 1 tests)
Expected results: 52
Unexpected results: 3
  subtest: 3 (3 fail)

Unexpected Results
------------------
toolkit/components/printing/tests/browser_modal_print.js
  FAIL Test timed out -
  FAIL Uncaught exception received from previously timed out test - focus listener not removed before the end of test
  FAIL Found a browser window after previous test timed out -

This is from me running the test directly as:

xvfb-run ./mach test toolkit/components/printing/tests/browser_modal_print.js