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Re: Towards a better testsuite

From: Gérard Talbot <www-style@gtalbot.org>
Date: Mon, 28 Mar 2016 22:39:39 -0400
To: Geoffrey Sneddon <me@gsnedders.com>
Cc: www-style list <www-style@w3.org>
Message-ID: <0cdacabb0312f28c82a9ec34b1fad93e@gtalbot.org>
Le 2016-03-24 13:00, Geoffrey Sneddon a écrit :
> Hi,
> 
> A bunch of us got together at TPAC last year to talk about how we
> could make the CSS testsuite more useful to more people.
> <https://www.w3.org/2015/10/28-testing-minutes.html> has minutes of
> the breakout session we had on Plenary day, though plenty more talk
> happened at other times. There's been some discussion on
> public-css-testsuite too, for those of you who don't subscribe there
> (you totally should!). Having spoken to Alan, we thought it was best
> to take much of this to the whole group. I'll probably start
> reappearing on telecons soon, too, all with ulterior motives, of
> course.
> 
> Fundamentally the situation with testing the web platform at the
> moment is that we essentially have three large repositories of tests:
> test262 (from ECMA TC-39, focused on their specs), csswg-test (from
> us), and web-platform-tests (covering everything else). From the point
> of view of all browser vendors, it'd be great if we were all sharing
> the vast majority of tests we write—and we're not anywhere near there
> yet.
> 
> The current status, as I understand it, is: test262 I believe people
> are mostly running old versions of and contributing little to;
> Microsoft is running weekly updated versions of csswg-test and Gecko
> is running a several-year-old version with no realistic plan to update
> it, nobody contributes that much (a tiny subset of Gecko stuff is
> automatically synced, but the vast majority is not);
> web-platform-tests is run by Microsoft semi-regularly, is run with
> two-way syncing from Gecko and Servo, with plans by Blink and
> Microsoft to get there AIUI, and with more in the way of contributions
> than either of the other two repositories. WebKit just aren't running
> anything, far as I'm aware. The only other group I'm aware of running
> anything is Prince, running a small subset of an old version of
> csswg-test.
> 
> Speaking to people across all browsers about why they're generally
> contributing more to web-platform-tests than csswg-test, there's a
> more or less uniform answer: there's too much friction. Metadata and
> review are the two parts held up as reasons; metadata because it means
> that existing tests can't simply be added to the testsuite (and you're
> then having to justify far more time to release the tests), review
> because often enough comments come back months later by which time
> everyone working on it has moved on and doesn't have time to address
> minor nits.


minor nits?


> 
> I went through all of the all of the metadata in
> <https://lists.w3.org/Archives/Public/public-css-testsuite/2015Oct/0004.html>;
> there's rough agreement on removing much of what we currently have.
> That said, I think it's worthwhile to reiterate that requiring *any*
> metadata causes friction. Tests written by browser vendors are rarely
> a file or two which is quick to add metadata too. I know in general
> people seem interested in using the same infrastructure to run both
> web-platform-tests and csswg-test, which essentially requires the
> metadata required to run the tests be identical across the two.
> 
> The other significant complication when it comes to csswg-test is the
> build system. Because of the necessity of building the testsuite first
> it makes it more complicated to fix tests when they're failing; you
> have to know how to find the source file and then be able to build the
> testsuite after fixing it. Historically the build system existed to
> deal with the variety in what UAs support, whether they supported HTML
> and/or XHTML; this is a far smaller deal nowadays—of the UAs running
> the CSS testsuite or likely to do so in the future, the only one I'm
> aware of that doesn't support both well is Servo (and that's likely to
> change so can possibly be ignored here).
> 
> This is, of course, all complicated by the need to be able to
> demonstrate that CR exit criteria have been met. For things in
> web-platform-tests, as I understand it, there's normally just been a
> copy of one directory that's been used to create the CR-exit
> testsuite. Aside from this, it's assumed that tests don't need to be
> run on a per-spec basis: yes, some things will get missed when
> building the CR-exit testsuite because they're in another directory
> because they're testing how multiple specs interact, but it's not
> worth the extra complexity to handle this, given the loss is normally
> small.
> 
> The other notable difference is in tooling: Mercurial is used with a
> git mirror, and then reviews are done split across Shepherd and
> public-css-testsuite and some issues filed on GitHub, and with some
> people expecting some pre-landing review through GitHub PRs and with
> some people pushing directly to Mercurial… Really everything would be
> simpler if we had *one* single way to do things. I'd much rather have
> everything on GitHub, review happening on PR submission, and nits and
> such like be reported as GitHub issues. This keeps everything in one
> place with tools most people are used to.
> 
> To outline what I'd like to see happen:
> 
> - Get rid of the build system, replacing many of it's old errors with
> a lint tool that tests for them.


I do not understand what you mean by get rid of the build system and 
replace it with a lint tool.


> - Policy changes to get rid of all metadata in the common case.
> - Change the commit policy. (Require review first, require no new lint 
> errors.)
> 
> Long-term it's probably worth considering merging the whole thing into
> web-platform-tests, so we have all the W3C tests in one place.
> 
> I realise this omits a lot of detail in a fair few places: I'm just
> trying to start off with something not *too* ginormous. :)
> 
> /gsnedders

To me, any serious discussion about good tests, good testing and better 
testsuite has to start with fixing known incorrect tests. Incorrect 
tests documented as such. Reported as such. And then also address a) 
tests that can not fail, b) tests that do not test what they claim (or 
believe) to be testing.

Gérard
Received on Tuesday, 29 March 2016 02:40:19 UTC

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