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Re: FW: In a quick glance, all of the whitespace test file are invalid tests that don't prove anything

From: Gérard Talbot <css21testsuite@gtalbot.org>
Date: Tue, 2 Mar 2010 09:03:53 -0800
Message-ID: <c06bd67d534f65150bec94c1658b4f0c.squirrel@cp3.shieldhost.com>
To: "Melissa Newman" <melissa@newmanfamily.org>
Cc: public-css-testsuite@w3.org

> how
> can anybody realistically tell the difference, with the naked eye,
> between a
> tab, 8 single white spaces, 16 half white spaces, or 4 double white
> spaces?
> You can't,

I agree with you. Testcases should avoid relying on/expecting the tester
counting and figuring out how many white spaces (of various kinds) there

This is the same problem with testcases which expect the tester to be
able to see, measure (or compare) a 9px (or 12px or 18px) difference
between 2 objects with the naked eye.

> Plus, we should have images that are exact measurements.  One for mm,
> one
> for inches, etc.  So if an end result of a test is supposed to have a
> space
> of 10mm, the tester can clearly see that the end results are 10 mm.

Creating custom (vertical and horizontal) measurement rulers (for in,
mm, cm, px, etc.) is rather easy to do. I have submitted 2 for the test

What is unacceptable is that a few testcases expect user agents to be
able to render distance like 2.54mm (9.6px) or 15.24mm (or 57.6px)
precisely and then ask/invite the tester to check if there is red in the

There is no normative restraint or requirement regarding how fraction of
a pixel is supposed to be handled by user agents. Each/all user agents
have implementation limits and various capability limitations.

regards, Gérard
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Received on Tuesday, 2 March 2010 17:04:39 UTC

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