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multicol-margin-001 test: review comments

From: Gérard Talbot <css21testsuite@gtalbot.org>
Date: Sat, 29 Jun 2013 00:02:11 -0400
Message-ID: <c2d12e350e6fb72eb740570ab3e4512c.squirrel@ed-sh-cp3.entirelydigital.com>
To: "Håkon Wium Lie" <howcome@opera.com>
Cc: "Public CSS Testsuite mailing list" <public-css-testsuite@w3.org>
Håkon,

[nightly-unstable]
http://test.csswg.org/suites/css3-multicol/nightly-unstable/html4/multicol-margin-001.htm

[src]
http://test.csswg.org/source/contributors/opera/submitted/multicol/multicol-margin-001.xht

As far as I can understand, this test is supposed to be verifying that
the top margin of the first block child element of a multicol element
does not collapse with the top margin of the multicol element. Please
correct me if it isn't the case.


--------


line 11: body {
	margin: 0;
}
line 14: p {
	border-bottom: 2em solid white;
	margin-bottom: 1em;
}

These rules are not part of the test itself. The <p> has no content
anyway in this non-self-describing test.
We usually prefer to use/rely on browser defaults for body margins and p
margins. This way, tests can be shorter and more straightforward and
they also will work on browsers with different body margins and p
margins.
There is no need in such tests for resetting those (body and p) margins.

--------

line 19: 	font-family: ahem;
line 20: 	font-size: 1em;

Whenever the Ahem font is used, we need to set a font-size whose
computed value will be dividable by 5px without a remainer. We do this
to avoid rounding issues and to ensure accurate vertical positioning of
content on the baseline, mostly for the Linux platform.

"
If the test uses the Ahem font, make sure its computed font-size is a
multiple of 5px, otherwise baseline alignment may be rendered
inconsistently (due to rounding errors introduced by certain platforms'
font APIs). We suggest to use a minimum computed font-size of 20px.
"
http://wiki.csswg.org/test/format#acceptable-test-formats

And so its current associated reftest would need to be updated to
reflect this too.

All the multi-column tests submitted by Opera will need to be adjusted
on this font-size of Ahem font issue.

--------

line 26: position: relative;
line 37: div::after {
	 content: "";
	 background: white;
	 height: 1em;
	 width: 2em;
	 position: absolute;
	 right: 0;
	 bottom: 0;
	 display: block;
line 46: }

I do not see the reason for the generated 2x1 white rectangle in the
test. If margin-top of first child collapses with the margin-top of the
multi-column element, then we will see a bright green
32px-wide-by-16px-tall rectangle at the bottom right corner. If
margin-top of first child does *not* collapse with the margin-top of the
multi-column element, then we should see such bright green
32px-wide-by-16px-tall rectangle at the top left corner. And so, the
comparison with the reftest should work by itself; the lime stripes
position and dimension would need to be identical.

So, I think that the div::after rule is not needed, not required in the
test and that line 26 is also not needed, not necessary.

As is, the test is still a correct one but it's imprecise, not
straightforward, streamlined.

Gérard
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Received on Saturday, 29 June 2013 04:02:40 UTC

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