refactor: extract toggle-state helpers shared by F9 and F12

The F12 commit (554b32d) flagged this as a follow-up: ~120 lines of capture-state and display-saved logic were duplicated between modules/ai-vterm.el and modules/eshell-vterm-config.el. The only differences were the default direction (right for F9, below for F12) and the customization name for the fallback size. Extract the shared logic into modules/cj-window-toggle.el so both consumers reduce to thin delegates that pass their state-var symbols and defaults. The state vars stay where they were, so existing tests against each consumer's helpers keep working.

10 new tests cover the parameterized helpers in isolation. All consumer tests still pass.

1 files changed, 188 insertions, 0 deletions

diff --git a/tests/test-cj-window-toggle.el b/tests/test-cj-window-toggle.el
new file mode 100644
index 00000000..c6273463
--- /dev/null
+++ b/tests/test-cj-window-toggle.el
@@ -0,0 +1,188 @@
+;;; test-cj-window-toggle.el --- Tests for shared toggle-state helpers -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; cj-window-toggle.el provides parameterized capture-state and
+;; display-saved helpers shared by ai-vterm.el (F9) and
+;; eshell-vterm-config.el (F12).  Each consumer holds its own pair of
+;; state variables (last-direction symbol + last-size integer/float)
+;; and passes the variable symbols to the helpers.  These tests cover
+;; the helpers in isolation against a fresh pair of test-only vars.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'cj-window-toggle)
+
+(defvar test-cj-window-toggle--last-direction nil)
+(defvar test-cj-window-toggle--last-size nil)
+
+(ert-deftest test-cj-window-toggle-capture-records-right-split ()
+  "Normal: right-split window writes direction=right and integer body-cols."
+  (save-window-excursion
+    (delete-other-windows)
+    (let ((right (split-window (selected-window) nil 'right))
+          (test-cj-window-toggle--last-direction nil)
+          (test-cj-window-toggle--last-size nil))
+      (cj/window-toggle-capture-state
+       right 'right
+       'test-cj-window-toggle--last-direction
+       'test-cj-window-toggle--last-size)
+      (should (eq test-cj-window-toggle--last-direction 'right))
+      (should (integerp test-cj-window-toggle--last-size))
+      (should (= test-cj-window-toggle--last-size
+                 (window-body-width right))))))
+
+(ert-deftest test-cj-window-toggle-capture-records-below-split ()
+  "Normal: below-split window writes direction=below and integer body-lines."
+  (save-window-excursion
+    (delete-other-windows)
+    (let ((below (split-window (selected-window) nil 'below))
+          (test-cj-window-toggle--last-direction nil)
+          (test-cj-window-toggle--last-size nil))
+      (cj/window-toggle-capture-state
+       below 'below
+       'test-cj-window-toggle--last-direction
+       'test-cj-window-toggle--last-size)
+      (should (eq test-cj-window-toggle--last-direction 'below))
+      (should (integerp test-cj-window-toggle--last-size))
+      (should (= test-cj-window-toggle--last-size
+                 (window-body-height below))))))
+
+(ert-deftest test-cj-window-toggle-capture-falls-back-to-default-direction ()
+  "Boundary: window filling the frame uses the supplied default direction."
+  (save-window-excursion
+    (delete-other-windows)
+    (let ((root (selected-window))
+          (test-cj-window-toggle--last-direction nil)
+          (test-cj-window-toggle--last-size nil))
+      (cj/window-toggle-capture-state
+       root 'below
+       'test-cj-window-toggle--last-direction
+       'test-cj-window-toggle--last-size)
+      (should (eq test-cj-window-toggle--last-direction 'below)))))
+
+(ert-deftest test-cj-window-toggle-capture-noop-on-nil-window ()
+  "Error: nil window leaves both state vars unchanged."
+  (let ((test-cj-window-toggle--last-direction 'sentinel-dir)
+        (test-cj-window-toggle--last-size 0.123))
+    (cj/window-toggle-capture-state
+     nil 'right
+     'test-cj-window-toggle--last-direction
+     'test-cj-window-toggle--last-size)
+    (should (eq test-cj-window-toggle--last-direction 'sentinel-dir))
+    (should (= test-cj-window-toggle--last-size 0.123))))
+
+(ert-deftest test-cj-window-toggle-capture-noop-on-deleted-window ()
+  "Error: a deleted window leaves both state vars unchanged."
+  (let ((test-cj-window-toggle--last-direction 'sentinel-dir)
+        (test-cj-window-toggle--last-size 0.123)
+        (dead (save-window-excursion
+                (delete-other-windows)
+                (let ((w (split-window (selected-window) nil 'right)))
+                  (delete-window w)
+                  w))))
+    (cj/window-toggle-capture-state
+     dead 'right
+     'test-cj-window-toggle--last-direction
+     'test-cj-window-toggle--last-size)
+    (should (eq test-cj-window-toggle--last-direction 'sentinel-dir))
+    (should (= test-cj-window-toggle--last-size 0.123))))
+
+(ert-deftest test-cj-window-toggle-display-saved-uses-defaults-when-state-nil ()
+  "Normal: nil state -> direction=edge of default, size=default."
+  (let (received-alist
+        (test-cj-window-toggle--last-direction nil)
+        (test-cj-window-toggle--last-size nil))
+    (cl-letf (((symbol-function 'display-buffer-in-direction)
+               (lambda (_b a) (setq received-alist a) 'fake-window)))
+      (cj/window-toggle-display-saved
+       'fake-buf
+       '((inhibit-same-window . t))
+       'test-cj-window-toggle--last-direction
+       'below
+       'test-cj-window-toggle--last-size
+       0.7))
+    (should (eq (cdr (assq 'direction received-alist)) 'bottom))
+    (should (= (cdr (assq 'window-height received-alist)) 0.7))
+    (should (eq (cdr (assq 'inhibit-same-window received-alist)) t))))
+
+(ert-deftest test-cj-window-toggle-display-saved-maps-below-to-bottom ()
+  "Normal: saved below + integer size -> bottom edge, body-lines cons."
+  (let (received-alist
+        (test-cj-window-toggle--last-direction 'below)
+        (test-cj-window-toggle--last-size 12))
+    (cl-letf (((symbol-function 'display-buffer-in-direction)
+               (lambda (_b a) (setq received-alist a) 'fake-window)))
+      (cj/window-toggle-display-saved
+       'fake-buf nil
+       'test-cj-window-toggle--last-direction
+       'below
+       'test-cj-window-toggle--last-size
+       0.7))
+    (should (eq (cdr (assq 'direction received-alist)) 'bottom))
+    (should (equal (cdr (assq 'window-height received-alist))
+                   '(body-lines . 12)))
+    (should-not (assq 'window-width received-alist))))
+
+(ert-deftest test-cj-window-toggle-display-saved-maps-right-to-rightmost ()
+  "Normal: saved right + integer size -> rightmost edge, body-columns cons."
+  (let (received-alist
+        (test-cj-window-toggle--last-direction 'right)
+        (test-cj-window-toggle--last-size 80))
+    (cl-letf (((symbol-function 'display-buffer-in-direction)
+               (lambda (_b a) (setq received-alist a) 'fake-window)))
+      (cj/window-toggle-display-saved
+       'fake-buf nil
+       'test-cj-window-toggle--last-direction
+       'right
+       'test-cj-window-toggle--last-size
+       0.5))
+    (should (eq (cdr (assq 'direction received-alist)) 'rightmost))
+    (should (equal (cdr (assq 'window-width received-alist))
+                   '(body-columns . 80)))
+    (should-not (assq 'window-height received-alist))))
+
+(ert-deftest test-cj-window-toggle-display-saved-strips-conflicting-entries ()
+  "Boundary: caller-supplied direction/size are removed; saved values win."
+  (let (received-alist
+        (test-cj-window-toggle--last-direction 'right)
+        (test-cj-window-toggle--last-size 30))
+    (cl-letf (((symbol-function 'display-buffer-in-direction)
+               (lambda (_b a) (setq received-alist a) 'fake-window)))
+      (cj/window-toggle-display-saved
+       'fake-buf
+       '((direction . above)
+         (window-width . 0.2)
+         (window-height . 0.3)
+         (inhibit-same-window . t))
+       'test-cj-window-toggle--last-direction
+       'right
+       'test-cj-window-toggle--last-size
+       0.5))
+    (should (eq (cdr (assq 'direction received-alist)) 'rightmost))
+    (should (equal (cdr (assq 'window-width received-alist))
+                   '(body-columns . 30)))
+    (should-not (assq 'window-height received-alist))
+    (should (eq (cdr (assq 'inhibit-same-window received-alist)) t))))
+
+(ert-deftest test-cj-window-toggle-display-saved-passes-float-size-through ()
+  "Boundary: float size passes through as a fraction (no body-N wrapping)."
+  (let (received-alist
+        (test-cj-window-toggle--last-direction 'below)
+        (test-cj-window-toggle--last-size nil))
+    (cl-letf (((symbol-function 'display-buffer-in-direction)
+               (lambda (_b a) (setq received-alist a) 'fake-window)))
+      (cj/window-toggle-display-saved
+       'fake-buf nil
+       'test-cj-window-toggle--last-direction
+       'below
+       'test-cj-window-toggle--last-size
+       0.4))
+    (should (eq (cdr (assq 'direction received-alist)) 'bottom))
+    (should (= (cdr (assq 'window-height received-alist)) 0.4))))
+
+(provide 'test-cj-window-toggle)
+;;; test-cj-window-toggle.el ends here