[TASK] Add TestCase for Value\Color

[JakeQZ]

This covers expected behaviour for CSS level 3
(some of which is also covered by more general tests).

Also included are some commented-out tests for CSS Color Module Level 4, support for which is yet to be implemented,
as well as for some syntaxes that should be rejected (but currently are not).

Precursor to resolving #755 and supporting CSS Color Module Level 4.

[JakeQZ]

@oliverklee, not sure how you feel about having commented-out tests, but it seemed to me, for now, a convenient way of capturing what needs to be done.

[coveralls]

coverage: 40.95% (+1.1%) from 39.862%
when pulling 94448c2 on task/color-test
into 1312700 on main.

[oliverklee]

not sure how you feel about having commented-out tests, but it seemed to me, for now, a convenient way of capturing what needs to be done.

I'm okay with those.

For still-to-be-done test cases, I prefer markTestIncomplete, and for still-to-be-done data provider cases, I slightly prefer // comments over /* */ comments as those make re-enabling single cases a bit less of a hassle.

[JakeQZ]

I slightly prefer // comments over /* */ comments as those make re-enabling single cases a bit less of a hassle.

With

/*
someCode();
//*/

the code can be temporarily uncommented by simply adding a forward-slash at the start of the comment:

//*
someCode();
//*/

[oliverklee]

@JakeQZ Is this something to backport?

[JakeQZ]

@JakeQZ Is this something to backport?

It would be needed if we wanted to backport #797 and its follow-up. But see #797 (comment). I think we are wasting our time with the backports, and should cut a 9.0 release as soon as #755 is resolved.