1 files changed, 246 insertions, 0 deletions
diff --git a/tests/test-custom-comments-comment-simple-divider.el b/tests/test-custom-comments-comment-simple-divider.el
new file mode 100644
index 00000000..a61e6b4c
--- /dev/null
+++ b/tests/test-custom-comments-comment-simple-divider.el
@@ -0,0 +1,246 @@
+;;; test-custom-comments-comment-simple-divider.el --- Tests for cj/comment-simple-divider -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for the cj/comment-simple-divider function from custom-comments.el
+;;
+;; This function generates a simple 3-line comment divider banner:
+;; - Top line: comment-start + decoration chars
+;; - Middle line: comment-start + text
+;; - Bottom line: comment-start + decoration chars
+;;
+;; We test the NON-INTERACTIVE implementation (cj/--comment-simple-divider)
+;; to avoid mocking user prompts. This follows our testing best practice
+;; of separating business logic from UI interaction.
+;;
+;; Cross-Language Testing Strategy:
+;; - Comprehensive testing in Emacs Lisp (our primary language)
+;; - Representative testing in Python and C (hash-based and C-style comments)
+;; - Function handles comment syntax generically, so testing 3 syntaxes
+;;   proves cross-language compatibility
+;; - See test-custom-comments-delete-buffer-comments.el for detailed rationale
+
+;;; Code:
+
+(require 'ert)
+(require 'testutil-general)
+
+;; Add modules directory to load path
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+
+;; Stub dependencies before loading the module
+(defvar cj/custom-keymap (make-sparse-keymap)
+  "Stub keymap for testing.")
+
+;; Now load the actual production module
+(require 'custom-comments)
+
+;;; Test Helpers
+
+(defun test-simple-divider-at-column (column-pos comment-start comment-end decoration-char text length)
+  "Test cj/--comment-simple-divider at COLUMN-POS indentation.
+Insert spaces to reach COLUMN-POS, then call cj/--comment-simple-divider with
+COMMENT-START, COMMENT-END, DECORATION-CHAR, TEXT, and LENGTH.
+Returns the buffer string for assertions."
+  (with-temp-buffer
+    (when (> column-pos 0)
+      (insert (make-string column-pos ?\s)))
+    (cj/--comment-simple-divider comment-start comment-end decoration-char text length)
+    (buffer-string)))
+
+;;; Emacs Lisp Tests (Primary Language - Comprehensive Coverage)
+
+;;; Normal Cases
+
+(ert-deftest test-simple-divider-elisp-basic ()
+  "Should generate simple 3-line divider in emacs-lisp style."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "-" "Section Header" 70)))
+    ;; Should have 3 lines
+    (should (= 3 (length (split-string result "\n" t))))
+    ;; Each line should start with ;;
+    (should (string-match-p "^;; -" result))
+    ;; Middle line should contain text
+    (should (string-match-p ";; Section Header" result))))
+
+(ert-deftest test-simple-divider-elisp-custom-decoration ()
+  "Should use custom decoration character."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "=" "Header" 70)))
+    (should (string-match-p ";; =" result))
+    (should-not (string-match-p ";; -" result))))
+
+(ert-deftest test-simple-divider-elisp-custom-text ()
+  "Should include custom text in middle line."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "-" "Custom Text Here" 70)))
+    (should (string-match-p ";; Custom Text Here" result))))
+
+(ert-deftest test-simple-divider-elisp-custom-length ()
+  "Should respect custom length."
+  (let* ((result (test-simple-divider-at-column 0 ";;" "" "-" "Header" 50))
+         (lines (split-string result "\n" t)))
+    ;; Should have 3 lines
+    (should (= 3 (length lines)))
+    ;; First and last lines (decoration) should be approximately 50 chars
+    (should (<= (length (car lines)) 51))
+    (should (>= (length (car lines)) 48))
+    (should (<= (length (car (last lines))) 51))
+    (should (>= (length (car (last lines))) 48))))
+
+(ert-deftest test-simple-divider-elisp-empty-text ()
+  "Should handle empty text string."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "-" "" 70)))
+    ;; Should still generate 3 lines
+    (should (= 3 (length (split-string result "\n" t))))
+    ;; Middle line should just be comment-start
+    (should (string-match-p "^;; *\n" result))))
+
+(ert-deftest test-simple-divider-elisp-at-column-0 ()
+  "Should work at column 0."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "-""Header" 70)))
+    ;; First character should be semicolon
+    (should (string-prefix-p ";;" result))))
+
+(ert-deftest test-simple-divider-elisp-indented ()
+  "Should work when indented."
+  (let ((result (test-simple-divider-at-column 4 ";;" "" "-""Header" 70)))
+    ;; Result should start with spaces
+    (should (string-prefix-p "    ;;" result))
+    ;; All lines should be indented
+    (dolist (line (split-string result "\n" t))
+      (should (string-prefix-p "    ;;" line)))))
+
+;;; Boundary Cases
+
+(ert-deftest test-simple-divider-elisp-minimum-length ()
+  "Should work with minimum viable length at column 0."
+  ;; Minimum length at column 0: 2 (;;) + 1 (space) + 1 (space) + 3 (dashes) = 7
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "-""" 7)))
+    (should (= 3 (length (split-string result "\n" t))))))
+
+(ert-deftest test-simple-divider-elisp-minimum-length-indented ()
+  "Should work with minimum viable length when indented."
+  ;; At column 4, minimum is 4 + 2 + 1 + 1 + 3 = 11
+  (let ((result (test-simple-divider-at-column 4 ";;" "" "-""" 11)))
+    (should (= 3 (length (split-string result "\n" t))))))
+
+(ert-deftest test-simple-divider-elisp-very-long-length ()
+  "Should handle very long length."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "-""Header" 200)))
+    (should (= 3 (length (split-string result "\n" t))))
+    ;; Decoration lines should be very long
+    (let ((first-line (car (split-string result "\n" t))))
+      (should (> (length first-line) 100)))))
+
+(ert-deftest test-simple-divider-elisp-unicode-decoration ()
+  "Should handle unicode decoration character."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "─""Header" 70)))
+    (should (string-match-p "─" result))))
+
+(ert-deftest test-simple-divider-elisp-unicode-text ()
+  "Should handle unicode in text."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "-""Hello 👋 مرحبا café" 70)))
+    (should (string-match-p "👋" result))
+    (should (string-match-p "مرحبا" result))
+    (should (string-match-p "café" result))))
+
+(ert-deftest test-simple-divider-elisp-very-long-text ()
+  "Should handle very long text (may wrap or truncate)."
+  (let* ((long-text (make-string 100 ?x))
+         (result (test-simple-divider-at-column 0 ";;" "" "-"long-text 70)))
+    ;; Should still generate output (behavior may vary)
+    (should (= 3 (length (split-string result "\n" t))))
+    ;; Middle line should contain some of the text
+    (should (string-match-p "xxx" result))))
+
+(ert-deftest test-simple-divider-elisp-comment-end-empty ()
+  "Should handle empty comment-end correctly."
+  (let ((result (test-simple-divider-at-column 0 ";;" "" "-""Header" 70)))
+    (should (= 3 (length (split-string result "\n" t))))
+    ;; Lines should not have trailing comment-end
+    (should-not (string-match-p ";;.*;;$" result))))
+
+(ert-deftest test-simple-divider-elisp-max-indentation ()
+  "Should handle maximum practical indentation."
+  (let ((result (test-simple-divider-at-column 60 ";;" "" "-""Header" 100)))
+    (should (= 3 (length (split-string result "\n" t))))
+    ;; All lines should start with 60 spaces
+    (dolist (line (split-string result "\n" t))
+      (should (string-prefix-p (make-string 60 ?\s) line)))))
+
+;;; Error Cases
+
+(ert-deftest test-simple-divider-elisp-length-too-small-column-0 ()
+  "Should error when length is too small at column 0."
+  (should-error
+   (test-simple-divider-at-column 0 ";;" "" "-" "Header" 5)
+   :type 'error))
+
+(ert-deftest test-simple-divider-elisp-length-too-small-indented ()
+  "Should error when length is too small for indentation level."
+  (should-error
+   (test-simple-divider-at-column 10 ";;" "" "-" "Header" 15)
+   :type 'error))
+
+(ert-deftest test-simple-divider-elisp-negative-length ()
+  "Should error with negative length."
+  (should-error
+   (test-simple-divider-at-column 0 ";;" "" "-" "Header" -10)
+   :type 'error))
+
+(ert-deftest test-simple-divider-elisp-zero-length ()
+  "Should error with zero length."
+  (should-error
+   (test-simple-divider-at-column 0 ";;" "" "-" "Header" 0)
+   :type 'error))
+
+(ert-deftest test-simple-divider-elisp-nil-decoration ()
+  "Should error when decoration-char is nil."
+  (should-error
+   (test-simple-divider-at-column 0 ";;" "" nil "Header" 70)
+   :type 'wrong-type-argument))
+
+(ert-deftest test-simple-divider-elisp-nil-text ()
+  "Should error when text is nil."
+  (should-error
+   (test-simple-divider-at-column 0 ";;" "" "-" nil 70)
+   :type 'wrong-type-argument))
+
+(ert-deftest test-simple-divider-elisp-non-integer-length ()
+  "Should error when length is not an integer."
+  (should-error
+   (test-simple-divider-at-column 0 ";;" "" "-""Header" "not-a-number")
+   :type 'wrong-type-argument))
+
+;;; Python Tests (Hash-based comments)
+
+(ert-deftest test-simple-divider-python-basic ()
+  "Should generate simple divider with Python comment syntax."
+  (let ((result (test-simple-divider-at-column 0 "#" "" "-""Section" 70)))
+    (should (= 3 (length (split-string result "\n" t))))
+    (should (string-match-p "^# -" result))
+    (should (string-match-p "# Section" result))))
+
+(ert-deftest test-simple-divider-python-indented ()
+  "Should handle indented Python comments."
+  (let ((result (test-simple-divider-at-column 4 "#" "" "=""Function Section" 70)))
+    (should (string-prefix-p "    #" result))
+    (should (string-match-p "Function Section" result))))
+
+;;; C Tests (C-style comments)
+
+(ert-deftest test-simple-divider-c-block-comments ()
+  "Should generate simple divider with C block comment syntax."
+  (let ((result (test-simple-divider-at-column 0 "/*" "*/" "-""Section" 70)))
+    (should (= 3 (length (split-string result "\n" t))))
+    (should (string-match-p "^/\\* -" result))
+    (should (string-match-p "/\\* Section" result))
+    ;; Should include comment-end
+    (should (string-match-p "\\*/" result))))
+
+(ert-deftest test-simple-divider-c-line-comments ()
+  "Should generate simple divider with C line comment syntax."
+  (let ((result (test-simple-divider-at-column 0 "//" "" "=""Header" 70)))
+    (should (= 3 (length (split-string result "\n" t))))
+    (should (string-match-p "^// =" result))
+    (should (string-match-p "// Header" result))))
+
+(provide 'test-custom-comments-comment-simple-divider)
+;;; test-custom-comments-comment-simple-divider.el ends here