1270585 - Opening modal whilst a script runs causes WebDriver:ExecuteScript/ExecuteAsyncScript to return immediately with a null result

Status: REOPENED

Description

[James Graham [:jgraham]]

In [8]: import marionette
     
    In [9]: m = marionette.Marionette()
     
    In [10]: m.start_session()
    Out[10]:
    {u'XULappId': u'{ec8030f7-c20a-464f-9b0e-13a3a9e97384}',
     u'acceptSslCerts': False,
     u'appBuildId': u'20160504043118',
     u'browserName': u'Firefox',
     u'browserVersion': u'49.0a1',
     u'command_id': 1,
     u'device': u'desktop',
     u'platform': u'LINUX',
     u'platformName': u'Linux',
     u'platformVersion': u'3.13.0-34-generic',
     u'proxy': {},
     u'raisesAccessibilityExceptions': False,
     u'rotatable': False,
     u'specificationLevel': 0,
     u'takesElementScreenshot': True,
     u'takesScreenshot': True,
     u'version': u'49.0a1'}
     
    In [11]: m.execute_script("return 1")
    Out[11]: 1
     
    In [12]: m.execute_script("alert(1); return 1") 

This isn't clearly the right thing to do, for example it would break a test that opened a window which spawned an alert, and then navigated that window [1]

[1] https://fiddle.jshell.net/wqansk7c/7/?utm_source=website&utm_medium=embed&utm_campaign=wqansk7c

Comment 2

[Andreas Tolfsen ⦗:ato⦘]

This could be a conformance problem.

As Jim Evans pointed out to me in #webdriver, there is also a likely
specification change necessary here to figure out what the expected
behaviour is meant to be.

Comment 3

[Henrik Skupin (:whimboo) [⌚️UTC+2]]

The current WebDriver spec states:

> If at any point during the algorithm a user prompt appears, abort all subsequent substeps of this algorithm, and return success with data null.

So isn't it the behavior we currently have? The example of comment 0 only references an alert, but not a different window. Also the provided link is a 404 now.

Andreas, what do you think?

Comment 4

[Andreas Tolfsen ⦗:ato⦘]

I just tried this with the Python client and it appears we return
immediately without any errors:

> >>> m.navigate("https://sny.no")
> >>> m.execute_script("alert('hi')")

So I would say we are doing the expected thing here.

Comment 5

[Henrik Skupin (:whimboo) [⌚️UTC+2]]

Actually based on my investigation and needinfo request on bug 1459118, this actually seems to be relevant and currently unclear in the spec. Means we indeed may return too early.

Comment 6

[Henrik Skupin (:whimboo) [⌚️UTC+2]]

So we discussed this issue in our WebDriver Meeting (https://wiki.mozilla.org/WebDriver/Meetings/2018-07-30) today, and agreed that this is conformant to the latest WebDriver spec. Any appearing user prompt should has to immediately stop the script execution.

Comment 7

[Henrik Skupin (:whimboo) [⌚️UTC+2]]

There is more discussion in the #webdriver channel based on our outcome and as such https://github.com/w3c/webdriver/issues/1153 has been reopened. Which means that this bug is not yet done. :/