From e43f76ab94fdaed8361eeec6a18d47a9551c10ff Mon Sep 17 00:00:00 2001
From: Craig Jennings <c@cjennings.net>
Date: Thu, 14 May 2026 03:55:27 -0500
Subject: test(ui-navigation): cover split-and-follow + undo-kill-buffer

Sibling tests covered `toggle-window-split` and the window-resize sticky map. This batch covers:

- `cj/split-and-follow-right`: split-window-right + other-window + consult-buffer in order.
- `cj/split-and-follow-below`: split-window-below + other-window + consult-buffer in order.
- `cj/undo-kill-buffer`: with no arg, opens the head of `recentf-list` that isn't currently visited; with N=1, opens the second entry; empty list -> no-op.

Top-level defvars for `recentf-mode` and `recentf-list` so let-bindings reach the dynamic vars under lexical scope.
---
 tests/test-ui-navigation-split-follow-undo-kill.el | 108 +++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 tests/test-ui-navigation-split-follow-undo-kill.el

diff --git a/tests/test-ui-navigation-split-follow-undo-kill.el b/tests/test-ui-navigation-split-follow-undo-kill.el
new file mode 100644
index 00000000..74c1e2fc
--- /dev/null
+++ b/tests/test-ui-navigation-split-follow-undo-kill.el
@@ -0,0 +1,108 @@
+;;; test-ui-navigation-split-follow-undo-kill.el --- Tests for the split-and-follow + undo-kill-buffer commands -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Sibling tests cover `toggle-window-split' and the window-resize
+;; sticky map.  This file covers the remaining three commands:
+;;
+;;   cj/split-and-follow-right
+;;   cj/split-and-follow-below
+;;   cj/undo-kill-buffer
+;;
+;; `split-window-*', `consult-buffer', `find-file', and `recentf'
+;; primitives are stubbed.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'ui-navigation)
+
+;; Top-level defvar so let-bindings reach the dynamic var under
+;; lexical scope.
+(defvar recentf-mode nil)
+(defvar recentf-list nil)
+
+;;; cj/split-and-follow-right
+
+(ert-deftest test-ui-navigation-split-right-splits-and-prompts ()
+  "Normal: split-and-follow-right calls split-window-right then consult-buffer."
+  (let ((sequence nil))
+    (cl-letf (((symbol-function 'split-window-right)
+               (lambda (&rest _) (push 'split sequence)))
+              ((symbol-function 'other-window)
+               (lambda (&rest _) (push 'other sequence)))
+              ((symbol-function 'consult-buffer)
+               (lambda (&rest _) (push 'consult sequence))))
+      (cj/split-and-follow-right))
+    (should (equal (reverse sequence) '(split other consult)))))
+
+;;; cj/split-and-follow-below
+
+(ert-deftest test-ui-navigation-split-below-splits-and-prompts ()
+  "Normal: split-and-follow-below calls split-window-below then consult-buffer."
+  (let ((sequence nil))
+    (cl-letf (((symbol-function 'split-window-below)
+               (lambda (&rest _) (push 'split sequence)))
+              ((symbol-function 'other-window)
+               (lambda (&rest _) (push 'other sequence)))
+              ((symbol-function 'consult-buffer)
+               (lambda (&rest _) (push 'consult sequence))))
+      (cj/split-and-follow-below))
+    (should (equal (reverse sequence) '(split other consult)))))
+
+;;; 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."
+  (let ((opened nil)
+        (recentf-mode t)
+        (recentf-list '("/tmp/dead.org" "/tmp/alive.txt")))
+    (cl-letf (((symbol-function 'require) (lambda (&rest _) t))
+              ((symbol-function 'recentf-mode) (lambda (&rest _) t))
+              ;; Pretend /tmp/alive.txt is open in some buffer.
+              ((symbol-function 'buffer-list)
+               (lambda (&rest _)
+                 (list (let ((b (get-buffer-create "*test-alive*")))
+                         (with-current-buffer b
+                           (setq buffer-file-name "/tmp/alive.txt"))
+                         b))))
+              ((symbol-function 'find-file)
+               (lambda (f) (setq opened f))))
+      (unwind-protect
+          (cj/undo-kill-buffer 0)
+        (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."
+  (let ((opened nil)
+        (recentf-mode t)
+        (recentf-list '("/tmp/a.org" "/tmp/b.org" "/tmp/c.org")))
+    (cl-letf (((symbol-function 'require) (lambda (&rest _) t))
+              ((symbol-function 'recentf-mode) (lambda (&rest _) t))
+              ((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))
+    (should (equal opened "/tmp/b.org"))))
+
+(ert-deftest test-ui-navigation-undo-kill-buffer-no-op-when-list-empty ()
+  "Boundary: when the recently-killed list is empty, find-file isn't called."
+  (let ((opened nil)
+        (recentf-mode t)
+        (recentf-list nil))
+    (cl-letf (((symbol-function 'require) (lambda (&rest _) t))
+              ((symbol-function 'recentf-mode) (lambda (&rest _) t))
+              ((symbol-function 'buffer-list) (lambda (&rest _) nil))
+              ((symbol-function 'find-file)
+               (lambda (f) (setq opened f))))
+      (cj/undo-kill-buffer 0))
+    (should-not opened)))
+
+(provide 'test-ui-navigation-split-follow-undo-kill)
+;;; test-ui-navigation-split-follow-undo-kill.el ends here
-- 
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