Re: [Frame Timing] Web platform tests

On 2015/06/16 6:55, Michael Blain wrote:
> Hi all,
> Here are a few Web Platform tests for the Frame TIming API.
> I understand that Mozilla, Chrome and IE have all pretty much decided to
> gate Frame Timing on the Performance Observer spec, so some of the
> details of the calls will change, but this is what we've been testing
> Chrome's implementation against.
> Any feedback would be appreciated!

Thanks for contributing these.

Please bear in mind that we would like to use these tests on test 
machines which are often under considerable load and have limited resources.

For example, to avoid intermittent failures, when writing animation 
tests we normally assume a worst-case scenario where frames might be as 
much as 100s apart.

 From glancing at these tests it seems we're assuming a 5ms difference 
between triggering a render and the time recorded on the render entry. 
Is that correct? If so it would be quite unsuitable for the kind of test 
environment we (and I suspect others) use. I'd suggest these tests 
should be written in such a way that they don't make any assumptions 
about timeliness but just test, for example, the order/existence of 
events, their relative times etc.

On a further note, the description of startTime seems to have been 
(incorrectly?) reverted.[1]

The previous text that spelled out that it corresponds to the time 
passed to rAF callbacks for that frame made much more sense.[2] I bring 
this up here because the test appears to be following the updated text 
but that seems undesirable.[3]

Best regards,


[2] As introduced here:
[3] As discussed here:

Received on Tuesday, 16 June 2015 01:46:10 UTC