Bug: Intermittent browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js | Uncaught exception - at chrome://mochikit/content/tests/SimpleTest/EventUtils.js:2817 - Error: No data transfer object after synthesizing the mouse!
Status: RESOLVED
Priority: P5
Resolution: DUPLICATE
Created: 2021-09-09 22:23:05+00:00
Resolved: 2022-08-13 13:13:53+00:00

**Filed by:** apavel [at] mozilla.com
**Parsed log:** https://treeherder.mozilla.org/logviewer?job_id=351069905&repo=mozilla-beta
**Full log:** https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/C7_hXnN4TGW2NVjZ5W9kfw/runs/0/artifacts/public/logs/live_backing.log

---
```
task 2021-09-09T20:50:19.936Z] 20:50:19     INFO - TEST-START | browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js
[task 2021-09-09T20:50:19.974Z] 20:50:19     INFO - GECKO(1588) | JavaScript error: resource:///modules/UrlbarInput.jsm, line 2942: TypeError: event.target.closest is not a function
[task 2021-09-09T20:50:19.976Z] 20:50:19     INFO - TEST-INFO | started process screencapture
[task 2021-09-09T20:50:20.244Z] 20:50:20     INFO - TEST-INFO | screencapture: exit 0
[task 2021-09-09T20:50:20.244Z] 20:50:20     INFO - Buffered messages logged at 20:50:19
[task 2021-09-09T20:50:20.245Z] 20:50:20     INFO - Entering test bound 
[task 2021-09-09T20:50:20.245Z] 20:50:20     INFO - TEST-PASS | browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js | Should be in the default state - 
[task 2021-09-09T20:50:20.245Z] 20:50:20     INFO - The last visible item in the nav-bar has ID: fxa-toolbar-menu-button
[task 2021-09-09T20:50:20.246Z] 20:50:20     INFO - Buffered messages finished
[task 2021-09-09T20:50:20.247Z] 20:50:20     INFO - TEST-UNEXPECTED-FAIL | browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js | Uncaught exception - at chrome://mochikit/content/tests/SimpleTest/EventUtils.js:2817 - Error: No data transfer object after synthesizing the mouse!
[task 2021-09-09T20:50:20.247Z] 20:50:20     INFO - Stack trace:
[task 2021-09-09T20:50:20.247Z] 20:50:20     INFO - synthesizeDragOver@chrome://mochikit/content/tests/SimpleTest/EventUtils.js:2817:11
[task 2021-09-09T20:50:20.247Z] 20:50:20     INFO - synthesizeDrop@chrome://mochikit/content/tests/SimpleTest/EventUtils.js:2939:52
[task 2021-09-09T20:50:20.247Z] 20:50:20     INFO - simulateItemDrag@chrome://mochitests/content/browser/browser/components/customizableui/test/head.js:228:17
[task 2021-09-09T20:50:20.247Z] 20:50:20     INFO - @chrome://mochitests/content/browser/browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js:49:19
[task 2021-09-09T20:50:20.248Z] 20:50:20     INFO - Leaving test bound 
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - Console message: [JavaScript Error: "TypeError: event.target.closest is not a function" {file: "resource:///modules/UrlbarInput.jsm" line: 2942}]
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - _on_mousedown@resource:///modules/UrlbarInput.jsm:2942:26
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - handleEvent@resource:///modules/UrlbarInput.jsm:425:23
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - synthesizeMouseAtPoint@chrome://mochikit/content/tests/SimpleTest/EventUtils.js:628:32
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - synthesizeMouse@chrome://mochikit/content/tests/SimpleTest/EventUtils.js:562:10
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - synthesizeMouseAtCenter@chrome://mochikit/content/tests/SimpleTest/EventUtils.js:735:10
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - synthesizeDragOver@chrome://mochikit/content/tests/SimpleTest/EventUtils.js:2805:26
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - synthesizeDrop@chrome://mochikit/content/tests/SimpleTest/EventUtils.js:2939:52
[task 2021-09-09T20:50:20.249Z] 20:50:20     INFO - simulateItemDrag@chrome://mochitests/content/browser/browser/components/customizableui/test/head.js:228:17
[task 2021-09-09T20:50:20.250Z] 20:50:20     INFO - @chrome://mochitests/content/browser/browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js:49:19
[task 2021-09-09T20:50:20.250Z] 20:50:20     INFO - 
[task 2021-09-09T20:50:20.250Z] 20:50:20     INFO - GECKO(1588) | MEMORY STAT | vsize 8262MB | residentFast 455MB | heapAllocated 209MB
[task 2021-09-09T20:50:20.250Z] 20:50:20     INFO - TEST-OK | browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js | took 47ms
[task 2021-09-09T20:50:20.251Z] 20:50:20     INFO - Not taking screenshot here: see the one that was previously logged
[task 2021-09-09T20:50:20.251Z] 20:50:20     INFO - TEST-UNEXPECTED-FAIL | browser/components/customizableui/test/browser_968565_insert_before_hidden_items.js | Found an unexpected tab at the end of test run: about:blank - 
[task 2021-09-09T20:50:20.252Z] 20:50:20     INFO - checking window state
```