test-org-table/sort-lines: Failing test on macOS

["Rudolf Adamkovič" <salutis@me.com>]

Howdy, howdy!

I see the test failure below on macOS.

Test test-org-table/sort-lines condition:

  (ert-test-failed
   ((should
     (equal "| a | x |\n| B | 4 |\n| c | 3 |\n"
            (org-test-with-temp-text "| <point>a | x |\n| c | 3 |\n| B | 4 |\n"
            ... ...)))
    :form
    (equal "| a | x |\n| B | 4 |\n| c | 3 |\n"
           #("| B | 4 |\n| a | x |\n| c | 3 |\n" 0 9
             (face org-table)
             10 19
             (face org-table)
             20 29
             (face org-table)))
    :value nil :explanation
    (array-elt 2
               (different-atoms
                (97 "#x61" "?a")
                (66 "#x42" "?B")))))
 FAILED  796/952  test-org-table/sort-lines (0.003410 sec)
   at ../lisp/test-org-table.el:1880

The isolated part of the test file that fails:

(let ((original-string-collate-lessp (symbol-function 'string-collate-lessp)))
  (cl-letf (((symbol-function 'string-collate-lessp)
             (lambda (s1 s2 &optional _locale ignore-case)
               (funcall original-string-collate-lessp
                        s1 s2 "C" nil))))
    (should
     (equal "| a | x |\n| B | 4 |\n| c | 3 |\n"
            (org-test-with-temp-text "| <point>a | x |\n| c | 3 |\n| B | 4 |\n"
                                     (org-table-sort-lines nil ?a)
                                     (buffer-string))))))

If I understand, "a" should be less than "B" when under "C" locale when
ignoring case (nil) , right?  Yet, I get the following:

(string-collate-lessp "a" "B" "C" nil)  ; => nil

[FYI: If I replace nil with t, the procedure returns nil too.]

Tested on Emacs 29 (adaa2fc90e) and Org 9.5.5 (580f28614).

Rudy
-- 
"It is no paradox to say that in our most theoretical moods we may be
nearest to our most practical applications."
-- Alfred North Whitehead, 1861-1947

Rudolf Adamkovič <salutis@me.com> [he/him]
Studenohorská 25
84103 Bratislava
Slovakia