feat: undead-buffers: Add `cj/make-buffer-undead` function and tests

Introduce a new function `cj/make-buffer-undead` that appends a
buffer name to the `cj/undead-buffer-list`, preventing it from being
killed. This comes along with a suite of tests to check various
scenarios and edge cases for handling undead buffers.

Additionally, add tests for related functions:
`cj/kill-buffer-or-bury-alive`, `cj/kill-buffer-and-window`, and
others to ensure they correctly manage buffers, particularly with
undead-status considerations.

Refactor `undead-buffer-list` naming for consistency and clarity in
the module.

1 files changed, 134 insertions, 0 deletions

diff --git a/tests/test-undead-buffers-make-buffer-undead.el b/tests/test-undead-buffers-make-buffer-undead.el
new file mode 100644
index 00000000..823bb56e
--- /dev/null
+++ b/tests/test-undead-buffers-make-buffer-undead.el
@@ -0,0 +1,134 @@
+;;; test-undead-buffers-make-buffer-undead.el --- Tests for cj/make-buffer-undead -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for the cj/make-buffer-undead function from undead-buffers.el
+
+;;; Code:
+
+(require 'ert)
+(require 'undead-buffers)
+(require 'testutil-general)
+
+;;; Setup and Teardown
+
+(defun test-make-buffer-undead-setup ()
+  "Setup for make-buffer-undead tests."
+  (cj/create-test-base-dir))
+
+(defun test-make-buffer-undead-teardown ()
+  "Teardown for make-buffer-undead tests."
+  (cj/delete-test-base-dir))
+
+;;; Normal Cases
+
+(ert-deftest test-make-buffer-undead-valid-name-should-add-to-list ()
+  "Adding a valid buffer name should add it to the undead buffer list."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (let ((orig (copy-sequence cj/undead-buffer-list)))
+        (unwind-protect
+            (progn
+              (cj/make-buffer-undead "*test-buffer*")
+              (should (member "*test-buffer*" cj/undead-buffer-list)))
+          (setq cj/undead-buffer-list orig)))
+    (test-make-buffer-undead-teardown)))
+
+(ert-deftest test-make-buffer-undead-existing-name-should-not-duplicate ()
+  "Adding an existing buffer name should not create duplicates."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (let ((orig (copy-sequence cj/undead-buffer-list)))
+        (unwind-protect
+            (progn
+              (cj/make-buffer-undead "*test-dup*")
+              (cj/make-buffer-undead "*test-dup*")
+              (should (= 1 (cl-count "*test-dup*" cj/undead-buffer-list :test #'string=))))
+          (setq cj/undead-buffer-list orig)))
+    (test-make-buffer-undead-teardown)))
+
+(ert-deftest test-make-buffer-undead-multiple-additions-should-preserve-order ()
+  "Adding multiple buffer names should preserve order."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (let ((orig (copy-sequence cj/undead-buffer-list)))
+        (unwind-protect
+            (progn
+              (cj/make-buffer-undead "*first*")
+              (cj/make-buffer-undead "*second*")
+              (cj/make-buffer-undead "*third*")
+              (let ((added-items (seq-drop cj/undead-buffer-list (length orig))))
+                (should (equal added-items '("*first*" "*second*" "*third*")))))
+          (setq cj/undead-buffer-list orig)))
+    (test-make-buffer-undead-teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-make-buffer-undead-whitespace-only-name-should-add ()
+  "Adding a whitespace-only name should succeed."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (let ((orig (copy-sequence cj/undead-buffer-list)))
+        (unwind-protect
+            (progn
+              (cj/make-buffer-undead "   ")
+              (should (member "   " cj/undead-buffer-list)))
+          (setq cj/undead-buffer-list orig)))
+    (test-make-buffer-undead-teardown)))
+
+(ert-deftest test-make-buffer-undead-very-long-name-should-add ()
+  "Adding a very long buffer name should succeed."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (let ((orig (copy-sequence cj/undead-buffer-list))
+            (long-name (make-string 1000 ?x)))
+        (unwind-protect
+            (progn
+              (cj/make-buffer-undead long-name)
+              (should (member long-name cj/undead-buffer-list)))
+          (setq cj/undead-buffer-list orig)))
+    (test-make-buffer-undead-teardown)))
+
+(ert-deftest test-make-buffer-undead-unicode-name-should-add ()
+  "Adding a buffer name with Unicode characters should succeed."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (let ((orig (copy-sequence cj/undead-buffer-list)))
+        (unwind-protect
+            (progn
+              (cj/make-buffer-undead "*test-🚀-buffer*")
+              (should (member "*test-🚀-buffer*" cj/undead-buffer-list)))
+          (setq cj/undead-buffer-list orig)))
+    (test-make-buffer-undead-teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-make-buffer-undead-empty-string-should-error ()
+  "Passing an empty string should signal an error."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (should-error (cj/make-buffer-undead ""))
+    (test-make-buffer-undead-teardown)))
+
+(ert-deftest test-make-buffer-undead-nil-should-error ()
+  "Passing nil should signal an error."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (should-error (cj/make-buffer-undead nil))
+    (test-make-buffer-undead-teardown)))
+
+(ert-deftest test-make-buffer-undead-number-should-error ()
+  "Passing a number should signal an error."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (should-error (cj/make-buffer-undead 42))
+    (test-make-buffer-undead-teardown)))
+
+(ert-deftest test-make-buffer-undead-symbol-should-error ()
+  "Passing a symbol should signal an error."
+  (test-make-buffer-undead-setup)
+  (unwind-protect
+      (should-error (cj/make-buffer-undead 'some-symbol))
+    (test-make-buffer-undead-teardown)))
+
+(provide 'test-undead-buffers-make-buffer-undead)
+;;; test-undead-buffers-make-buffer-undead.el ends here