[webkit-dev] C++ unit tests for WebKit?

[Hans Muller]

Thanks for the thoughtful reply.   It was exactly the "community's conventions and customs" that I was trying to get a handle on.   Not to put too fine a point on it, but I assume that adding unit tests to TestWebKitAPI or writing tests that depend on APIs defined in Internals.idl wouldn't be customary or conventional?    I'd been thinking about doing the latter (Internals.idl), just because it would enable testing some low level classes before everything we're working on had been integrated top to bottom.  Doing so could just be a private temporary change, since eventually it will be possible to exercise the code via public APIs.

- Hans


From: Adam Barth <abarth at webkit.org<mailto:abarth at webkit.org>>
To: Hans Muller <hmuller at adobe.com<mailto:hmuller at adobe.com>>
Cc: Benjamin Poulain <benjamin at webkit.org<mailto:benjamin at webkit.org>>, Konrad Piascik <kpiascik at rim.com<mailto:kpiascik at rim.com>>, webkit-dev <webkit-dev at lists.webkit.org<mailto:webkit-dev at lists.webkit.org>>
Subject: Re: [webkit-dev] C++ unit tests for WebKit?

Generally speaking, WebKit's testing philosophy is to test at API boundaries, typically either a given port's WebKit API or the web platform API.  The benefit of that approach is that it makes it easier for us to refactor the internals of WebCore without being constrained by fragile tests---only by API commitments.

In the case of CSS Exclusions, it's likely valuable to think about how you can test the feature via the web platform.  Developing a rich set of tests that use web platform APIs has a number of follow-on benefits that WebCore-internal testing doesn't, such as the ability to run the tests in other browsers and to contribute them to the W3C as part of the standards process.

Of course, this sort of one-size-fits-all testing strategy works well in come cases in less well in others.  I understand that other projects have different testing strategies that have worked well for them, but I would encourage you to try our the community's conventions and customs for a while to get a feel for which ones work well and which ones ought to be improved.

Adam


On Wed, Jul 11, 2012 at 3:44 PM, Hans Muller <hmuller at adobe.com<mailto:hmuller at adobe.com>> wrote:
It looks like Tools/TestWebKitAPI/Tests/WebCore just contains one small
KURL test. I could certainly add more for the Exclusions shape classes,
but I got that feeling that maybe you get about being the first to take a
table at an empty restaurant.  Perhaps it's just that most of the C++
classes in WebCore are too interdependent to merit unit testing?

- Hans


On 7/11/12 2:26 PM, "Benjamin Poulain" <benjamin at webkit.org<mailto:benjamin at webkit.org>> wrote:

>On Wed, Jul 11, 2012 at 2:23 PM, Hans Muller <hmuller at adobe.com<mailto:hmuller at adobe.com>> wrote:
>> Have the merits of C++ unit tests been debated before?  I noticed that
>>a bug
>> representing as much has been around since 2008
>> (https://bugs.webkit.org/show_bug.cgi?id=21010).  The last comment
>>(2009)
>> concludes with: "I'd be interested to hear other's thoughts."
>>Personally,
>> I'd like to be able to include unit tests with worthy C++ classes,
>>however I
>> would also like to hear other's thoughts.
>
>That has been discussed before.
>
>We have some C++ tests, see Tools/TestWebKitAPI/Tests/
>You can probably integrate yours in there.
>
>Cheers,
>Benjamin

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