[webkit-dev] Proposal for Device-Specific Layout Tests

Ryosuke Niwa rniwa at webkit.org
Tue Dec 4 16:43:04 PST 2018

On Tue, Dec 4, 2018 at 12:55 PM Jonathan Bedard <jbedard at apple.com> wrote:

> These directories would be along-side tests.

I don't like that platform-specific results are under LayoutTests/platform
and device-specific results are next to the tests. We should stick with
either convention, not mix them up.

If we were to match LayoutTests/platforms, we should probably put it under
LayoutTests/devices, or alternatively inside each platform's test
directory. Alternatively, I'd be fine if we moved platform specific results
to those subdirectories. But having both conventions used throughout would
be an insane mess.

It is different from how we treat platforms because platforms have
> historically been used to differentiate between different binary types,
> which doesn’t really apply here. We also have platform versions which we
> use for inheriting expectations between versions, that idea also doesn’t
> transfer well to the case.

I don't think these differences are all that interesting. The problem I
have with this approach is that this will be yet another concept new
contributor has to learn, and yet another layer of abstraction & a new set
of configurations we'd have to worry about when figuring out which test
expectation will be used & needs to be updated when WebKit's behavior

Creating new device-platforms would make EWS and running layout tests
> locally very confusing


> and wouldn’t really solve the run-a-test-twice problem.

Again, why?

We would have to have an entirely different set of results for each device
> type, and when running on-device tests, the user would have to be aware
> enough to use the platform which corresponds to the device (or devices)
> they had attached. This would be a pretty radical departure from the way
> things currently work, were iPhone 7 and iPad tests run with the rest of
> the iOS tests.

I don't see how treating iPhone 7 as a platform would pose any issue here.
It's like a variant of iOS port like Mountain Lion is a variant of macOS

What I also don't understand is what happens when iOS behavior changes
between iOS 10 and iOS 11 on iPhone 7. Where would the expected result live
for those two operating systems and how are they named?

- R. Niwa

On Dec 3, 2018, at 6:25 PM, Ryosuke Niwa <rniwa at webkit.org> wrote:
> Are those directories along side tests? If so, that seems very different
> from the approach we take with platforms. Why the discrepancy?
> Can't we just treat them as specific type of iOS platforms?
> - R. Niwa
> On Mon, Dec 3, 2018 at 4:05 PM Jonathan Bedard <jbedard at apple.com> wrote:
>> Hello everyone,
>> I have a proposal to make writing layout tests for specific types of
>> devices more straight-forward.
>> Currently, we name directories with the beginning of a device name, such
>> as ‘iphone7’ or ‘ipad’ and hope that those directory names match the name
>> of a device type in the associated port’s CUSTOM_DEVICE_CLASS. This causes
>> some problems, however, in a few circumstances. The first problem arises
>> when two ports have associated devices (such as watchOS and iOS), in this
>> case, a directory which maps to a device type on one port might not on
>> another. The second problem is that our current code for managing devices
>> assumes that devices can be booted on-demand, which is not the case in
>> on-device testing, where we need to run different sets of tests depending
>> on the type of device attached. The last (and most important) problem is
>> that we cannot run the same test twice on two different devices in a single
>> test run (ie, run test.html once on an iPhone and once on an iPad).
>> To resolve this, I propose 3 changes to how we organize layout tests.
>> 1) Allow *-expected.txt files to be device-specific <
>> https://bugs.webkit.org/show_bug.cgi?id=192162>
>> The idea here would be to optionally allow *-expected.txt files to be a
>> directory looking something like this:
>> dir/
>>     test.html
>>     test-expected/
>>         iPhone-7.txt
>> Under this scheme, the name of the .txt file would map directly to a
>> device type. Multiple device-specific expectations would be permitted, but
>> making sense of these results requires change #2.
>> 2) Support multiple results for a specific test <
>> https://bugs.webkit.org/show_bug.cgi?id=192163>
>> Similar to #1, we need to allow test results to be attributed to a device
>> type. This would be done with a similar scheme, where results for a test
>> would optionally be saved as a directory looking like this:
>> dir/
>>     test/
>>         iPhone-7-actual.txt
>>         iPhone-7-diff.txt
>>         iPhone-7-expected.txt
>>         iPhone-7-diff.html
>>         iPhone-8-actual.txt
>>         iPhone-8-diff.txt
>>         iPhone-8-expected.txt
>>         iPhone-8-diff.html
>> When reporting, results would be reported to as a new ‘queue’ of the form
>> '<queue>-<device>’.
>> 3) Provide device specific tags in test expectations <
>> https://bugs.webkit.org/show_bug.cgi?id=192164>
>> We already have Debug/Release as well as version tags in our test
>> expectations. The addition here would be device-type tags, those tags would
>> look like this:
>> [ iPhone 7 ] dir/test.html [ Pass ]
>> [ iPad ] dir/other-test.html [ Pass ]
>> These tags would allow for 2 features. The first is similar to existing
>> tags, allowing a certain test (or group of tests) to have different
>> expectations or to be skipped entirely on certain device types. The second
>> feature allows for tests and groups of tests to be run on multiple
>> different devices in a single instantiation of run-webkit-tests. For
>> example,
>> [ iPhone 7, iPad ] dir/some-dir/ [ Pass ]
>> would indicate that every test in dir/some-dir/ will be run on BOTH
>> iPhone 7 and iPad.
>> I would welcome anyone else’s thoughts on this.
>> Jonathan
>> _______________________________________________
>> webkit-dev mailing list
>> webkit-dev at lists.webkit.org
>> https://lists.webkit.org/mailman/listinfo/webkit-dev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-dev/attachments/20181204/b1c71472/attachment.html>

More information about the webkit-dev mailing list