Fix the date in the calendar mode line (bug#80069)

* lisp/calendar/calendar.el (calendar-redraw)
(calendar-other-month): Make sure that the mode line is updated
after cursor motion in case 'date' is used in
'calendar-mode-line-format'.
(calendar-set-date-style): Delete call to
calendar-update-mode-line because it is called in calendar-draw.
(calendar-generate-window): Delete calls to
calendar-update-mode-line and calendar-cursor-to-visible-date.
It's better for the caller to do it.
(calendar-basic-setup): Update cursor position and mode line.
* lisp/calendar/cal-move.el (calendar-goto-today): Delete
calendar-update-mode-line because calendar-move-hook is called
last.  This is consistent with other cal-move commands.
* test/lisp/calendar/calendar-tests.el
(calendar-test-date-in-mode-line): New test.

1 files changed, 31 insertions, 0 deletions

diff --git a/test/lisp/calendar/calendar-tests.el b/test/lisp/calendar/calendar-tests.el
index 2aef0bf827b..5fd974f952f 100644
--- a/test/lisp/calendar/calendar-tests.el
+++ b/test/lisp/calendar/calendar-tests.el
@@ -30,5 +30,36 @@
   (should (eq (calendar-date-is-valid-p (list 1 2)) nil))
   (should (eq (calendar-date-is-valid-p (list 5 1 2025)) t)))
 
+(ert-deftest calendar-test-date-in-calendar-mode-line ()
+  "Test whether the calendar mode line displays `date' correctly."
+  (save-window-excursion
+    (unwind-protect
+        (let* ((calendar-mode-line-format (list '(calendar-date-string date)))
+               (calendar-move-hook '(calendar-update-mode-line))
+               (today (calendar-current-date))
+               (month (calendar-extract-month today))
+               (year (calendar-extract-year today))
+               (cursor-date (calendar-gregorian-from-absolute
+                             (1+ (calendar-absolute-from-gregorian today)))))
+          (calendar)
+          (should (equal (string-trim mode-line-format)
+                         (calendar-date-string today)))
+          (calendar-forward-day 1)
+          (should (equal (string-trim mode-line-format)
+                         (calendar-date-string cursor-date)))
+          (calendar-goto-today)
+          (should (equal (string-trim mode-line-format)
+                         (calendar-date-string today)))
+          (calendar-cursor-to-visible-date cursor-date)
+          (calendar-redraw)
+          (should (equal (string-trim mode-line-format)
+                         (calendar-date-string cursor-date)))
+          (calendar-cursor-to-visible-date cursor-date)
+          (calendar-scroll-left)
+          (calendar-other-month month year)
+          (should (equal (string-trim mode-line-format)
+                         (calendar-date-string cursor-date))))
+      (kill-buffer calendar-buffer))))
+
 (provide 'calendar-tests)
 ;;; calendar-tests.el ends here