refactor(text-enclose): extract shared region-or-buffer bounds helper

The append/prepend/indent/dedent *-in-region-or-buffer commands each inlined the same (if (use-region-p) (region-beginning) (point-min)) / (region-end)/(point-max) block — four copies of the "operate on the region, else the whole buffer" contract. Extracted cj/--region-or-buffer-bounds as the single source of that decision and routed all four through it. Behavior is unchanged; the public-wrapper tests still pass.

This was the "extract a shared helper that decides the target range" option from the reconcile task. The sibling custom-ordering.el helpers (cj/--arrayify, cj/--unarrayify) already document an explicit (start end) contract accurately and are region-required by design, so they needed no docstring change — each pair now has one clear, consistent contract. Tests cover the helper for the region case, the no-region whole-buffer case, and an empty buffer.

2 files changed, 64 insertions, 24 deletions

diff --git a/modules/custom-text-enclose.el b/modules/custom-text-enclose.el
index ebfb44e9..e1b735a0 100644
--- a/modules/custom-text-enclose.el
+++ b/modules/custom-text-enclose.el
@@ -132,15 +132,21 @@ Returns the transformed string without modifying the buffer."
      (mapconcat (lambda (line) (concat line suffix)) lines-to-process "\n")
      (if has-trailing-newline "\n" ""))))
 
+(defun cj/--region-or-buffer-bounds ()
+  "Return a cons (START . END) for the active region, else the whole buffer.
+The single source of the region-or-buffer contract shared by the
+`*-in-region-or-buffer' commands: operate on the active region when one is
+active, otherwise the entire buffer."
+  (if (use-region-p)
+      (cons (region-beginning) (region-end))
+    (cons (point-min) (point-max))))
+
 (defun cj/append-to-lines-in-region-or-buffer (str)
   "Append STR to the end of each line in the region or entire buffer."
   (interactive "sEnter string to append: ")
-  (let* ((start-pos (if (use-region-p)
-                        (region-beginning)
-                      (point-min)))
-         (end-pos (if (use-region-p)
-                      (region-end)
-                    (point-max)))
+  (let* ((bounds (cj/--region-or-buffer-bounds))
+         (start-pos (car bounds))
+         (end-pos (cdr bounds))
          (text (buffer-substring start-pos end-pos))
          (insertion (cj/--append-to-lines text str)))
     (delete-region start-pos end-pos)
@@ -167,12 +173,9 @@ Returns the transformed string without modifying the buffer."
 (defun cj/prepend-to-lines-in-region-or-buffer (str)
   "Prepend STR to the beginning of each line in the region or entire buffer."
   (interactive "sEnter string to prepend: ")
-  (let* ((start-pos (if (use-region-p)
-                        (region-beginning)
-                      (point-min)))
-         (end-pos (if (use-region-p)
-                      (region-end)
-                    (point-max)))
+  (let* ((bounds (cj/--region-or-buffer-bounds))
+         (start-pos (car bounds))
+         (end-pos (cdr bounds))
          (text (buffer-substring start-pos end-pos))
          (insertion (cj/--prepend-to-lines text str)))
     (delete-region start-pos end-pos)
@@ -195,12 +198,9 @@ Returns the indented text without modifying the buffer."
 COUNT is the number of characters to indent (default 4).
 USE-TABS when non-nil (prefix argument) uses tabs instead of spaces."
   (interactive "p\nP")
-  (let* ((start-pos (if (use-region-p)
-                        (region-beginning)
-                      (point-min)))
-         (end-pos (if (use-region-p)
-                      (region-end)
-                    (point-max)))
+  (let* ((bounds (cj/--region-or-buffer-bounds))
+         (start-pos (car bounds))
+         (end-pos (cdr bounds))
          (text (buffer-substring start-pos end-pos))
          (insertion (cj/--indent-lines text count use-tabs)))
     (delete-region start-pos end-pos)
@@ -242,12 +242,9 @@ Returns the dedented text without modifying the buffer."
 COUNT is the number of characters to remove (default 4).
 Works on region if active, otherwise entire buffer."
   (interactive "p")
-  (let* ((start-pos (if (use-region-p)
-                        (region-beginning)
-                      (point-min)))
-         (end-pos (if (use-region-p)
-                      (region-end)
-                    (point-max)))
+  (let* ((bounds (cj/--region-or-buffer-bounds))
+         (start-pos (car bounds))
+         (end-pos (cdr bounds))
          (text (buffer-substring start-pos end-pos))
          (insertion (cj/--dedent-lines text count)))
     (delete-region start-pos end-pos)
diff --git a/tests/test-custom-text-enclose--region-or-buffer-bounds.el b/tests/test-custom-text-enclose--region-or-buffer-bounds.el
new file mode 100644
index 00000000..98992af8
--- /dev/null
+++ b/tests/test-custom-text-enclose--region-or-buffer-bounds.el
@@ -0,0 +1,43 @@
+;;; test-custom-text-enclose--region-or-buffer-bounds.el --- Tests for bounds helper -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Unit tests for cj/--region-or-buffer-bounds, the single source of the
+;; "operate on the active region, else the whole buffer" contract shared by
+;; the *-in-region-or-buffer editing commands.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'custom-text-enclose)
+
+;;; Normal Cases
+
+(ert-deftest test-ctenc-bounds-uses-region-when-active ()
+  "Normal: with an active region, returns its beginning and end."
+  (cl-letf (((symbol-function 'use-region-p) (lambda () t))
+            ((symbol-function 'region-beginning) (lambda () 3))
+            ((symbol-function 'region-end) (lambda () 8)))
+    (should (equal '(3 . 8) (cj/--region-or-buffer-bounds)))))
+
+(ert-deftest test-ctenc-bounds-uses-whole-buffer-when-no-region ()
+  "Normal: with no active region, returns the whole buffer's bounds."
+  (with-temp-buffer
+    (insert "line one\nline two\n")
+    (cl-letf (((symbol-function 'use-region-p) (lambda () nil)))
+      (should (equal (cons (point-min) (point-max))
+                     (cj/--region-or-buffer-bounds))))))
+
+;;; Boundary Cases
+
+(ert-deftest test-ctenc-bounds-empty-buffer-no-region ()
+  "Boundary: an empty buffer with no region yields equal start and end."
+  (with-temp-buffer
+    (cl-letf (((symbol-function 'use-region-p) (lambda () nil)))
+      (let ((b (cj/--region-or-buffer-bounds)))
+        (should (= (car b) (cdr b)))))))
+
+(provide 'test-custom-text-enclose--region-or-buffer-bounds)
+;;; test-custom-text-enclose--region-or-buffer-bounds.el ends here