1140294 - focused_chrome_window_handle fails if there is no active window

Status: RESOLVED FIXED

(Testing :: Firefox UI Tests, defect)

Description

[Henrik Skupin [:whimboo][⌚️UTC+1]]

Today we got the first report from Travis about a broken test. Looks like an intermittent failure given that we haven't seen it before.

Details can be found at:
https://travis-ci.org/mozilla/firefox-ui-tests/jobs/53308218

Traceback:
 0:42.46 TEST_START: MainThread test_windows.py TestBaseWindow.test_open_close
 0:43.28 TEST_END: MainThread ERROR, expected PASS
Traceback (most recent call last):
  File "/home/travis/build/mozilla/firefox-ui-tests/client/marionette/marionette_test.py", line 290, in run
    testMethod()
  File "/home/travis/build/mozilla/firefox-ui-tests/firefox_puppeteer/tests/test_windows.py", line 114, in test_open_close
    self.assertTrue(win1.focused)
  File "/home/travis/build/mozilla/firefox-ui-tests/firefox_puppeteer/ui/windows.py", line 203, in focused
    return self.handle == self._windows.focused_chrome_window_handle
  File "/home/travis/build/mozilla/firefox-ui-tests/firefox_puppeteer/ui/windows.py", line 50, in focused_chrome_window_handle
    """)
  File "/home/travis/.venv/local/lib/python2.7/site-packages/marionette_driver-0.2-py2.7.egg/marionette_driver/marionette.py", line 1369, in execute_script
    filename=os.path.basename(frame[0]))
  File "/home/travis/.venv/local/lib/python2.7/site-packages/marionette_driver-0.2-py2.7.egg/marionette_driver/decorators.py", line 36, in _
    return func(*args, **kwargs)
  File "/home/travis/.venv/local/lib/python2.7/site-packages/marionette_driver-0.2-py2.7.egg/marionette_driver/marionette.py", line 670, in _send_message
    self._handle_error(response)
  File "/home/travis/.venv/local/lib/python2.7/site-packages/marionette_driver-0.2-py2.7.egg/marionette_driver/marionette.py", line 725, in _handle_error
    raise errors.JavascriptException(message=message, status=status, stacktrace=stacktrace)
JavascriptException: JavascriptException: TypeError: win is null
stacktrace:
	execute_script @windows.py, line 50
	inline javascript, line 3
	src: "              return win.QueryInterface(Ci.nsIInterfaceRequestor)"

Code responsible for failures:
https://github.com/mozilla/firefox-ui-tests/blob/master/firefox_puppeteer/ui/windows.py#L43

What I think is that at this specific moment we may not have an active window? My suggestion would be to return None in case of win is null.

Comment 1

[Henrik Skupin [:whimboo][⌚️UTC+1]]

Attachment: github_pull_request.txt

Pretty interesting race condition. So our test catches a time when the focus is moving from window to the next one as it looks like. So activeWindow returns null. We can simply return None for focused_chrome_window_handle() in such a case.

Comment 2

[Chris Manchester (limited bugmail, email directly)]

Comment on attachment 8573784 [details] [review]
github_pull_request.txt

Question in github.

Comment 3

[Henrik Skupin [:whimboo][⌚️UTC+1]]

Comment on attachment 8573784 [details] [review]
github_pull_request.txt

Updated the PR given your feedback comments. I also added a new parameter to the open_window() method which implicitly checks for the focus state. I think that is way better then having each single test doing it on its own.

Comment 4

[Chris Manchester (limited bugmail, email directly)]

Comment on attachment 8573784 [details] [review]
github_pull_request.txt

I had a question about the API for open_window, but it's not really a blocker.

Comment 5

[Henrik Skupin [:whimboo][⌚️UTC+1]]

We clarified the remaining items on IRC. So the final PR got merged as:

https://github.com/mozilla/firefox-ui-tests/commit/f1123c7a4f3b9902e40a771e5bbab7c8eb2fc8ea