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Bug 25680 - Don't tell what User Agent MUST do
Summary: Don't tell what User Agent MUST do
Alias: None
Product: Browser Test/Tools WG
Classification: Unclassified
Component: WebDriver (show other bugs)
Version: unspecified
Hardware: All All
: P2 normal
Target Milestone: ---
Assignee: Browser Testing and Tools WG
QA Contact: Browser Testing and Tools WG
Depends on:
Blocks: 20860
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Reported: 2014-05-13 10:51 UTC by seva
Modified: 2015-10-26 03:07 UTC (History)
4 users (show)

See Also:


Description seva 2014-05-13 10:51:05 UTC
Section "10.1 Determining if an element is displayed" mentions that

"The User Agent MUST NOT allow negative scrolling."

Is trying to define what a User Agent MUST do out of scope of this spec?
Should we just delete that sentence or formulate it as a prescription for the WD remote end?
Comment 1 David Burns :automatedtester 2014-05-13 12:42:06 UTC
The spec is designed to tell the User Agent (the browser) what it MUST/SHOULD do or not do. 

In this case browsers never do negative scrolling but if they ever do we have it in writing that it should never be handled.
Comment 2 Andrey Botalov 2014-05-13 18:51:01 UTC
So that means that it should tell "The remote end MUST NOT allow negative scrolling."
Comment 3 seva 2014-05-15 01:00:36 UTC
David, I believe the distinction between (similarly sounding) "what browser should/must do" and "what WD remote end should/must make the browser do" is important. We know that the spec is for 'implementors of the WebDriver API', that it describes two components - local and remote ends - and that implementors are not necessarily people who have complete control over browser behavior in certain situations.

In the ideal situation, implementors of WebDriver are a browser vendor and they have some control, but even then WebDriver API doesn't feel right place to define what browser should/must do in WebDriver-irrelevant situations (such as supporting or not supporting negative scrolling); for that there are other specs.

Does this make sense?

We could defer it to the F2F or something since it doesn't appear to be blocking anything.

Now I also noticed several other places in the spec with 'user agent must/should'.
Comment 4 James Graham 2015-10-26 03:07:30 UTC
I agree with the premise of this bug, but I think all the instances are fixed now. If not please open specific bugs.