Eli Zaretskii <eliz@gnu.org> writes:

> However, I'm worried that we have no test for ucs-normalize, so it's
> hard to be sure the non-trivial functionality is unchanged, even
> though your changes are pretty straightforward.
>
> How about adding a test that uses the data in this file:
>
>   http://www.unicode.org/Public/UNIDATA/NormalizationTest.txt
>
> ucs-normalize claims to have passed an old version of this, but I see
> no existing way of re-running that test, did I miss something?

I don't see any evidence of an existing test.  I stared writing a new
one, and it's failing with the original ucs-normalize.el (or I'm
misunderstanding the requirements).

The first invariant to test is

    c2 ==  toNFC(c1) ==  toNFC(c2) == toNFC(c3)

(cX is column X, columns numbered from 1).

Line 15131 of NormalizationTest.txt has
# c1   c2      c3
1112E;1112E;11131 11127;1112E;11131 11127; # (◌𑄮; ◌𑄮; ◌𑄱◌𑄧; ◌𑄮; ◌𑄱◌𑄧; ) CHAKMA VOWEL SIGN O

So I think toNFC(c3) == c2 is equivalent to

    (equal (ucs-normalize-NFC-string
            (string #x11131 #x11127))
           (string #x1112E))

which gives nil.

Lines 15131 to 15139 and 16149 to 16289 are failing.  To check
invariants for a single line, load the attached ucs-normalize-tests.el,
put point at the beginning of the line and evaluate

        (ucs-normalize-tests--invariants-hold-p
         (ucs-normalize-tests--parse-column)
         (ucs-normalize-tests--parse-column)
         (ucs-normalize-tests--parse-column)
         (ucs-normalize-tests--parse-column)
         (ucs-normalize-tests--parse-column))