[webkit-dev] Rebaselining render tree dumps

Nikolas Zimmermann zimmermann at physik.rwth-aachen.de
Wed Dec 8 23:04:48 PST 2010

Am 08.12.2010 um 00:55 schrieb Ryosuke Niwa:

> Hi all,
> Since this would require a lot of rebaselines anyways, can we also  
> add some enhancements to DRT?
> I propose to an option to dump as text with images.  In many editing  
> tests, we don't need render tree dumps because we care more about  
> how DOM looks like before and after editing operations.  However, we  
> also need to verify that selection and caret are rendered properly  
> on multiple occasions, and the only way to do this right now is to  
> use a pixel test.  But even then, dumping render tree is not helpful  
> and almost harmful because it doesn't tell us how selection / caret  
> are rendered (this can never be tested by comparing text) and hides  
> some important information about DOM and makes us rebaseline tests  
> whenever there's slight change (that we don't care) in the render  
> tree.
> James (jamesr) and I talked about this on IRC, and he said this  
> feature will also be useful for repaint tests and canvas tests.  We  
> can implement this feature by adding dumpAsTextWithImage to  
> layoutTestController, which forces DRT to dump as text but also  
> outputs the png image.  For repainting tests, we can also add  
> dumpRepaintRects to output more information about painting.

Hi Ryosuke,

this feature is already available. I've implemented it for the svg/ 
dynamic-updates test, DRT hooks are available.
dumpAsText() takes an optional boolean parameter that toggles this.

// svg/dynamic-updates tests set enablePixelTesting=true, as we want  
to dump text + pixel results
if (window.layoutTestController)
     layoutTestController.dumpAsText(true /* enablePixelTesting */);

That will give you a "dumpAsText" result + a pixel test result. Hope  
that helps..


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