fix(ui-navigation): correct cj/undo-kill-buffer off-by-one on plain invocation

(interactive "p") forces arg >= 1, so the old (if arg (nth arg ...) (car ...)) always took the nth branch and plain M-S-z re-opened the second-most-recently-killed file. Index with (nth (1- arg) ...) so a numeric prefix is 1-based and no prefix re-opens the most recent. The two undo-kill tests now exercise the real no-prefix path (arg=1 reopens the first) and a 1-based numeric prefix; both failed against the bug and pass after. Filed a follow-up for a separate delq-vs-delete skip-visited defect found in the same function.

1 files changed, 7 insertions, 9 deletions

diff --git a/tests/test-ui-navigation-split-follow-undo-kill.el b/tests/test-ui-navigation-split-follow-undo-kill.el
index 74c1e2fc..b1d99020 100644
--- a/tests/test-ui-navigation-split-follow-undo-kill.el
+++ b/tests/test-ui-navigation-split-follow-undo-kill.el
@@ -54,8 +54,9 @@
 
 ;;; cj/undo-kill-buffer
 
-(ert-deftest test-ui-navigation-undo-kill-buffer-opens-most-recent ()
-  "Normal: with no arg, opens the head of recentf-list that isn't currently visited."
+(ert-deftest test-ui-navigation-undo-kill-buffer-no-prefix-opens-most-recent ()
+  "Normal: no prefix (arg=1, the value `\"p\"' yields) opens the most-recent
+non-visited entry, not the second."
   (let ((opened nil)
         (recentf-mode t)
         (recentf-list '("/tmp/dead.org" "/tmp/alive.txt")))
@@ -71,12 +72,12 @@
               ((symbol-function 'find-file)
                (lambda (f) (setq opened f))))
       (unwind-protect
-          (cj/undo-kill-buffer 0)
+          (cj/undo-kill-buffer 1)
         (when (get-buffer "*test-alive*") (kill-buffer "*test-alive*"))))
     (should (equal opened "/tmp/dead.org"))))
 
-(ert-deftest test-ui-navigation-undo-kill-buffer-honors-numeric-arg ()
-  "Normal: with N=1, opens the second non-visited entry from recentf-list."
+(ert-deftest test-ui-navigation-undo-kill-buffer-numeric-arg-is-one-based ()
+  "Normal: a numeric prefix is 1-based — N=2 opens the second non-visited entry."
   (let ((opened nil)
         (recentf-mode t)
         (recentf-list '("/tmp/a.org" "/tmp/b.org" "/tmp/c.org")))
@@ -85,10 +86,7 @@
               ((symbol-function 'buffer-list) (lambda (&rest _) nil))
               ((symbol-function 'find-file)
                (lambda (f) (setq opened f))))
-      ;; cj/undo-kill-buffer takes a prefix `arg' and indexes into the list
-      ;; with `(nth arg ...)` when arg is non-nil.  Passing 1 grabs the 2nd
-      ;; entry.
-      (cj/undo-kill-buffer 1))
+      (cj/undo-kill-buffer 2))
     (should (equal opened "/tmp/b.org"))))
 
 (ert-deftest test-ui-navigation-undo-kill-buffer-no-op-when-list-empty ()