Generate partial IDL fragments for CSS properties for WPT?

[gsnedders]

CSSOM defines up to three partial interfaces that are created for each supported property:

partial interface CSSStyleDeclaration {
  [CEReactions] attribute [LegacyNullToEmptyString] CSSOMString _camel_cased_attribute;
};
partial interface CSSStyleDeclaration {
  [CEReactions] attribute [LegacyNullToEmptyString] CSSOMString _webkit_cased_attribute;
};
partial interface CSSStyleDeclaration {
  [CEReactions] attribute [LegacyNullToEmptyString] CSSOMString _dashed_attribute;
};

It would be nice to have these tested in WPT, whether Reffy itself generates these or whether they're generated merely for the WPT export.

See also speced/bikeshed#549 for a Bikeshed feature request to add generation of these to Bikeshed, and w3c/csswg-drafts#5412 for potential pitfalls here (though as far as I'm aware no such property is currently defined)

[foolip]

I've previously experimented in that direction in foolip/wpt@e2c50fb and you have filed web-platform-tests/wpt#9113 where there's some discussion.

I did write code at one point to generate the Web IDL, which I can't find, but it's easy to do.

However, since there's more that can be checked in JS for each property than these attributes, like CSS.support and behavior of document.body.style.stuff, I wonder if it doesn't make the most sense to generate those tests in one place and not bother with the minimal help we'd get from using idlharness.js.

[gsnedders]

However, since there's more that can be checked in JS for each property than these attributes, like CSS.support and behavior of document.body.style.stuff, I wonder if it doesn't make the most sense to generate those tests in one place and not bother with the minimal help we'd get from using idlharness.js.

I think we want both?

[foolip]

Yes, and because we want both having the generated IDL isn't going to be all that useful, we can check the small number of things they would check together with the other tests, so that shallow tests for a property are in one place, with one naming convention. I think that'll be nicer to deal with when adding support and updating test expectations, at least.

[tidoust]

Summary of the discussion in #111 on this topic: generating the IDL is not that useful but having the IDL attribute names that each property generates is. Goal is thus to add a styleDeclaration key to property descriptions in CSS extracts that is an array with IDL attribute names. For instance:

 {
   "properties": {
     "align-content": {
       "styleDeclaration": ["align-content", "alignContent"]
     }
   }
 }

[tidoust]

All CSS properties descriptions now contain a styleDeclaration property.
Released in @webref/css@1.1.0.