feat(music): add test coverage for 7 functions, refactor with extracted helpersHEADmain

Add 47 new unit tests across 7 test files covering playlist-modified-p,
assert-valid-playlist-file, playlist-tracks, create-radio-station,
ensure-playlist-buffer, after-playlist-clear, and header-text.

Extract three helpers to reduce duplication: assert-m3u-files-exist (dedupes
2 identical guards), sync-playlist-file (dedupes 3 state-sync patterns),
and select-m3u-file (reusable M3U selection with cancel). Simplify
append-track-to-playlist nesting from 6 to 4 levels. Delete unused
cj/music-keymap-prefix variable.

8 files changed, 975 insertions, 36 deletions

diff --git a/modules/music-config.el b/modules/music-config.el
index d24018ac..46474a23 100644
--- a/modules/music-config.el
+++ b/modules/music-config.el
@@ -92,9 +92,6 @@
 (defvar cj/music-m3u-root cj/music-root
   "Directory where M3U playlists are saved and loaded.")
 
-(defvar cj/music-keymap-prefix (kbd "C-; m")
-  "Prefix keybinding for all music commands. Currently not auto-bound.")
-
 (defvar cj/music-file-extensions '("aac" "flac" "m4a" "mp3" "ogg" "opus" "wav")
   "List of valid music file extensions.")
 
@@ -223,6 +220,29 @@ Signals user-error if missing or deleted."
       (user-error "Playlist file no longer exists: %s"
                   (file-name-nondirectory cj/music-playlist-file))))))
 
+(defun cj/music--assert-m3u-files-exist ()
+  "Assert that M3U files exist in cj/music-m3u-root.
+Returns the list of (BASENAME . FULLPATH) conses. Signals user-error if none."
+  (let ((files (cj/music--get-m3u-files)))
+    (when (null files)
+      (user-error "No M3U files found in %s" cj/music-m3u-root))
+    files))
+
+(defun cj/music--sync-playlist-file (file-path)
+  "Set the playlist buffer's associated M3U file to FILE-PATH and reset point."
+  (with-current-buffer (cj/music--ensure-playlist-buffer)
+    (setq cj/music-playlist-file file-path)
+    (goto-char (point-min))))
+
+(defun cj/music--select-m3u-file (prompt)
+  "Prompt user to select an M3U file with PROMPT.
+Returns the full path to the selected file, or nil if cancelled."
+  (let* ((m3u-files (cj/music--assert-m3u-files-exist))
+         (choices (append (mapcar #'car m3u-files) '("(Cancel)")))
+         (choice (completing-read prompt choices nil t)))
+    (unless (string= choice "(Cancel)")
+      (cdr (assoc choice m3u-files)))))
+
 ;;; Commands: add/select
 
 (defun cj/music-add-directory-recursive (directory)
@@ -300,40 +320,31 @@ Prompts for M3U file selection with completion. Allows cancellation."
     (unless track
       (user-error "No track at point"))
     (let* ((track-path (emms-track-name track))
-           (m3u-files (cj/music--get-m3u-files)))
-      (when (null m3u-files)
-        (user-error "No M3U files found in %s" cj/music-m3u-root))
-      (let* ((choices (append (mapcar #'car m3u-files) '("(Cancel)")))
-             (choice (completing-read "Append track to playlist: " choices nil t)))
-        (if (string= choice "(Cancel)")
-            (message "Cancelled")
-          (let ((m3u-file (cdr (assoc choice m3u-files))))
-            (condition-case err
-                (progn
-                  (cj/music--append-track-to-m3u-file track-path m3u-file)
-                  (message "Added '%s' to %s"
-                           (file-name-nondirectory track-path)
-                           choice))
-              (error (message "Failed to append track: %s" (error-message-string err))))))))))
+           (m3u-file (cj/music--select-m3u-file "Append track to playlist: ")))
+      (if (not m3u-file)
+          (message "Cancelled")
+        (condition-case err
+            (progn
+              (cj/music--append-track-to-m3u-file track-path m3u-file)
+              (message "Added '%s' to %s"
+                       (file-name-nondirectory track-path)
+                       (file-name-nondirectory m3u-file)))
+          (error (message "Failed to append track: %s" (error-message-string err))))))))
 
 
 (defun cj/music-playlist-load ()
   "Load an M3U playlist from cj/music-m3u-root.
 Replaces current playlist."
   (interactive)
-  (let* ((pairs (cj/music--get-m3u-files)))
-    (when (null pairs)
-      (user-error "No M3U files found in %s" cj/music-m3u-root))
-    (let* ((choice-name (completing-read "Select playlist: " (mapcar #'car pairs) nil t))
-           (choice-file (cdr (assoc choice-name pairs))))
-      (unless (and choice-file (file-exists-p choice-file))
-        (user-error "Playlist file does not exist: %s" choice-name))
-      (emms-playlist-clear)
-      (emms-play-playlist choice-file)
-      (with-current-buffer (cj/music--ensure-playlist-buffer)
-        (setq cj/music-playlist-file choice-file)
-        (goto-char (point-min)))
-      (message "Loaded playlist: %s" choice-name))))
+  (let* ((pairs (cj/music--assert-m3u-files-exist))
+         (choice-name (completing-read "Select playlist: " (mapcar #'car pairs) nil t))
+         (choice-file (cdr (assoc choice-name pairs))))
+    (unless (and choice-file (file-exists-p choice-file))
+      (user-error "Playlist file does not exist: %s" choice-name))
+    (emms-playlist-clear)
+    (emms-play-playlist choice-file)
+    (cj/music--sync-playlist-file choice-file)
+    (message "Loaded playlist: %s" choice-name)))
 
 
 (defun cj/music-playlist-save ()
@@ -352,8 +363,8 @@ Offers completion over existing names but allows new names."
       (user-error "Aborted saving playlist"))
     (with-current-buffer (cj/music--ensure-playlist-buffer)
       (let ((emms-source-playlist-ask-before-overwrite nil))
-        (emms-playlist-save 'm3u full))
-      (setq cj/music-playlist-file full))
+        (emms-playlist-save 'm3u full)))
+    (cj/music--sync-playlist-file full)
     (message "Saved playlist: %s" filename)))
 
 
@@ -377,9 +388,7 @@ Offers completion over existing names but allows new names."
          (name (file-name-nondirectory file-path)))
     (emms-playlist-clear)
     (emms-play-playlist file-path)
-    (with-current-buffer (cj/music--ensure-playlist-buffer)
-      (setq cj/music-playlist-file file-path)
-      (goto-char (point-min)))
+    (cj/music--sync-playlist-file file-path)
     (message "Reloaded playlist: %s" name)))
 
 
diff --git a/tests/test-music-config--after-playlist-clear.el b/tests/test-music-config--after-playlist-clear.el
new file mode 100644
index 00000000..c23e2b5b
--- /dev/null
+++ b/tests/test-music-config--after-playlist-clear.el
@@ -0,0 +1,116 @@
+;;; test-music-config--after-playlist-clear.el --- Tests for playlist clear advice -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; Unit tests for cj/music--after-playlist-clear function.
+;; Tests the advice function that resets cj/music-playlist-file
+;; when the EMMS playlist is cleared.
+;;
+;; Test organization:
+;; - Normal Cases: Clears file variable, noop when no buffer
+;; - Boundary Cases: Already nil stays nil, idempotent on multiple calls
+;; - Error Cases: Killed buffer doesn't crash
+;;
+;;; Code:
+
+(require 'ert)
+
+;; Stub missing dependencies before loading music-config
+(defvar-keymap cj/custom-keymap
+  :doc "Stub keymap for testing")
+
+;; Add EMMS elpa directory to load path for batch testing
+(let ((emms-dir (car (file-expand-wildcards
+                      (expand-file-name "elpa/emms-*" user-emacs-directory)))))
+  (when emms-dir
+    (add-to-list 'load-path emms-dir)))
+
+(require 'emms)
+(require 'emms-playlist-mode)
+(require 'music-config)
+
+;;; Test helpers
+
+(defun test-after-clear--setup ()
+  "Create playlist buffer with a playlist file set."
+  (let ((buf (get-buffer-create cj/music-playlist-buffer-name)))
+    (with-current-buffer buf
+      (emms-playlist-mode)
+      (setq emms-playlist-buffer-p t))
+    (setq emms-playlist-buffer buf)
+    buf))
+
+(defun test-after-clear--teardown ()
+  "Clean up test playlist buffer."
+  (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+    (with-current-buffer buf
+      (setq cj/music-playlist-file nil))
+    (kill-buffer buf)))
+
+;;; Normal Cases
+
+(ert-deftest test-music-config--after-playlist-clear-normal-clears-file-variable ()
+  "Calling after-playlist-clear sets cj/music-playlist-file to nil."
+  (unwind-protect
+      (progn
+        (test-after-clear--setup)
+        (with-current-buffer cj/music-playlist-buffer-name
+          (setq cj/music-playlist-file "/path/to/playlist.m3u"))
+        (cj/music--after-playlist-clear)
+        (with-current-buffer cj/music-playlist-buffer-name
+          (should-not cj/music-playlist-file)))
+    (test-after-clear--teardown)))
+
+(ert-deftest test-music-config--after-playlist-clear-normal-noop-when-no-buffer ()
+  "Does nothing when playlist buffer doesn't exist."
+  (unwind-protect
+      (progn
+        ;; Ensure no buffer exists
+        (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+          (kill-buffer buf))
+        ;; Should not error
+        (cj/music--after-playlist-clear))
+    (test-after-clear--teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-music-config--after-playlist-clear-boundary-already-nil-stays-nil ()
+  "Already-nil playlist file remains nil after clear."
+  (unwind-protect
+      (progn
+        (test-after-clear--setup)
+        (with-current-buffer cj/music-playlist-buffer-name
+          (setq cj/music-playlist-file nil))
+        (cj/music--after-playlist-clear)
+        (with-current-buffer cj/music-playlist-buffer-name
+          (should-not cj/music-playlist-file)))
+    (test-after-clear--teardown)))
+
+(ert-deftest test-music-config--after-playlist-clear-boundary-multiple-calls-idempotent ()
+  "Multiple calls produce same result as single call."
+  (unwind-protect
+      (progn
+        (test-after-clear--setup)
+        (with-current-buffer cj/music-playlist-buffer-name
+          (setq cj/music-playlist-file "/path/to/playlist.m3u"))
+        (cj/music--after-playlist-clear)
+        (cj/music--after-playlist-clear)
+        (cj/music--after-playlist-clear)
+        (with-current-buffer cj/music-playlist-buffer-name
+          (should-not cj/music-playlist-file)))
+    (test-after-clear--teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-music-config--after-playlist-clear-error-killed-buffer-no-crash ()
+  "Killed buffer doesn't cause an error."
+  (let ((buf (test-after-clear--setup)))
+    (kill-buffer buf)
+    ;; Should not error when buffer is gone
+    (should-not (condition-case err
+                    (progn (cj/music--after-playlist-clear) nil)
+                  (error err)))))
+
+(provide 'test-music-config--after-playlist-clear)
+;;; test-music-config--after-playlist-clear.el ends here
diff --git a/tests/test-music-config--assert-valid-playlist-file.el b/tests/test-music-config--assert-valid-playlist-file.el
new file mode 100644
index 00000000..aca0eeb9
--- /dev/null
+++ b/tests/test-music-config--assert-valid-playlist-file.el
@@ -0,0 +1,131 @@
+;;; test-music-config--assert-valid-playlist-file.el --- Tests for playlist file validation -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; Unit tests for cj/music--assert-valid-playlist-file function.
+;; Tests the validation guard that ensures a playlist buffer has
+;; a valid, existing associated M3U file before operations proceed.
+;;
+;; Test organization:
+;; - Normal Cases: Valid file passes without error
+;; - Boundary Cases: Empty file, file exists but is empty
+;; - Error Cases: Nil file, nonexistent file, deleted file
+;;
+;;; Code:
+
+(require 'ert)
+(require 'testutil-general)
+
+;; Stub missing dependencies before loading music-config
+(defvar-keymap cj/custom-keymap
+  :doc "Stub keymap for testing")
+
+;; Add EMMS elpa directory to load path for batch testing
+(let ((emms-dir (car (file-expand-wildcards
+                      (expand-file-name "elpa/emms-*" user-emacs-directory)))))
+  (when emms-dir
+    (add-to-list 'load-path emms-dir)))
+
+(require 'emms)
+(require 'emms-playlist-mode)
+(require 'music-config)
+
+;;; Test helpers
+
+(defun test-assert--setup ()
+  "Create test base dir and ensure playlist buffer exists."
+  (cj/create-test-base-dir)
+  (let ((buf (get-buffer-create cj/music-playlist-buffer-name)))
+    (with-current-buffer buf
+      (emms-playlist-mode)
+      (setq emms-playlist-buffer-p t))
+    (setq emms-playlist-buffer buf)
+    buf))
+
+(defun test-assert--teardown ()
+  "Clean up test playlist buffer and temp files."
+  (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+    (with-current-buffer buf
+      (setq cj/music-playlist-file nil))
+    (kill-buffer buf))
+  (cj/delete-test-base-dir))
+
+;;; Normal Cases
+
+(ert-deftest test-music-config--assert-valid-playlist-file-normal-existing-file-passes ()
+  "Valid existing file does not signal error."
+  (test-assert--setup)
+  (unwind-protect
+      (let ((file (cj/create-temp-test-file "playlist-")))
+        (with-current-buffer (get-buffer cj/music-playlist-buffer-name)
+          (setq cj/music-playlist-file file))
+        ;; Should not error
+        (cj/music--assert-valid-playlist-file))
+    (test-assert--teardown)))
+
+(ert-deftest test-music-config--assert-valid-playlist-file-normal-file-with-content-passes ()
+  "Valid file with content does not signal error."
+  (test-assert--setup)
+  (unwind-protect
+      (let ((file (cj/create-temp-test-file-with-content "track1.mp3\ntrack2.mp3\n" "playlist-")))
+        (with-current-buffer (get-buffer cj/music-playlist-buffer-name)
+          (setq cj/music-playlist-file file))
+        (cj/music--assert-valid-playlist-file))
+    (test-assert--teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-music-config--assert-valid-playlist-file-boundary-empty-file-passes ()
+  "Empty but existing file does not signal error."
+  (test-assert--setup)
+  (unwind-protect
+      (let ((file (cj/create-temp-test-file "playlist-")))
+        (with-current-buffer (get-buffer cj/music-playlist-buffer-name)
+          (setq cj/music-playlist-file file))
+        ;; File exists but is empty - should still pass
+        (cj/music--assert-valid-playlist-file))
+    (test-assert--teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-music-config--assert-valid-playlist-file-error-nil-file-signals-user-error ()
+  "Nil cj/music-playlist-file signals user-error."
+  (test-assert--setup)
+  (unwind-protect
+      (progn
+        (with-current-buffer (get-buffer cj/music-playlist-buffer-name)
+          (setq cj/music-playlist-file nil))
+        (should-error (cj/music--assert-valid-playlist-file)
+                      :type 'user-error))
+    (test-assert--teardown)))
+
+(ert-deftest test-music-config--assert-valid-playlist-file-error-nonexistent-file-signals-user-error ()
+  "Nonexistent file path signals user-error."
+  (test-assert--setup)
+  (unwind-protect
+      (progn
+        (with-current-buffer (get-buffer cj/music-playlist-buffer-name)
+          (setq cj/music-playlist-file "/nonexistent/path/to/playlist.m3u"))
+        (should-error (cj/music--assert-valid-playlist-file)
+                      :type 'user-error))
+    (test-assert--teardown)))
+
+(ert-deftest test-music-config--assert-valid-playlist-file-error-deleted-file-signals-user-error ()
+  "File that existed but was deleted signals user-error."
+  (test-assert--setup)
+  (unwind-protect
+      (let ((file (cj/create-temp-test-file "playlist-")))
+        (with-current-buffer (get-buffer cj/music-playlist-buffer-name)
+          (setq cj/music-playlist-file file))
+        ;; Verify it passes first
+        (cj/music--assert-valid-playlist-file)
+        ;; Now delete the file
+        (delete-file file)
+        ;; Should now signal error
+        (should-error (cj/music--assert-valid-playlist-file)
+                      :type 'user-error))
+    (test-assert--teardown)))
+
+(provide 'test-music-config--assert-valid-playlist-file)
+;;; test-music-config--assert-valid-playlist-file.el ends here
diff --git a/tests/test-music-config--ensure-playlist-buffer.el b/tests/test-music-config--ensure-playlist-buffer.el
new file mode 100644
index 00000000..b7f9a8b7
--- /dev/null
+++ b/tests/test-music-config--ensure-playlist-buffer.el
@@ -0,0 +1,106 @@
+;;; test-music-config--ensure-playlist-buffer.el --- Tests for playlist buffer creation -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; Unit tests for cj/music--ensure-playlist-buffer function.
+;; Tests buffer creation, mode setup, and global variable assignment.
+;;
+;; Test organization:
+;; - Normal Cases: Creates new buffer, returns existing buffer
+;; - Boundary Cases: Wrong mode gets corrected, sets global variable
+;; - Error Cases: Killed buffer gets recreated, returns live buffer
+;;
+;;; Code:
+
+(require 'ert)
+
+;; Stub missing dependencies before loading music-config
+(defvar-keymap cj/custom-keymap
+  :doc "Stub keymap for testing")
+
+;; Add EMMS elpa directory to load path for batch testing
+(let ((emms-dir (car (file-expand-wildcards
+                      (expand-file-name "elpa/emms-*" user-emacs-directory)))))
+  (when emms-dir
+    (add-to-list 'load-path emms-dir)))
+
+(require 'emms)
+(require 'emms-playlist-mode)
+(require 'music-config)
+
+;;; Test helpers
+
+(defun test-ensure--teardown ()
+  "Clean up test playlist buffer."
+  (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+    (kill-buffer buf)))
+
+;;; Normal Cases
+
+(ert-deftest test-music-config--ensure-playlist-buffer-normal-creates-buffer-when-none-exists ()
+  "Creates a new playlist buffer when none exists."
+  (unwind-protect
+      (progn
+        ;; Kill any existing buffer
+        (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+          (kill-buffer buf))
+        (let ((result (cj/music--ensure-playlist-buffer)))
+          (should (bufferp result))
+          (should (buffer-live-p result))
+          (should (equal (buffer-name result) cj/music-playlist-buffer-name))))
+    (test-ensure--teardown)))
+
+(ert-deftest test-music-config--ensure-playlist-buffer-normal-returns-existing-buffer ()
+  "Returns existing buffer without recreating it."
+  (unwind-protect
+      (let* ((buf1 (cj/music--ensure-playlist-buffer))
+             (buf2 (cj/music--ensure-playlist-buffer)))
+        (should (eq buf1 buf2)))
+    (test-ensure--teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-music-config--ensure-playlist-buffer-boundary-wrong-mode-corrected ()
+  "Buffer in wrong mode gets corrected to emms-playlist-mode."
+  (unwind-protect
+      (progn
+        ;; Create buffer in fundamental-mode
+        (let ((buf (get-buffer-create cj/music-playlist-buffer-name)))
+          (with-current-buffer buf
+            (fundamental-mode)))
+        (let ((result (cj/music--ensure-playlist-buffer)))
+          (with-current-buffer result
+            (should (eq major-mode 'emms-playlist-mode)))))
+    (test-ensure--teardown)))
+
+(ert-deftest test-music-config--ensure-playlist-buffer-boundary-sets-global-variable ()
+  "Sets emms-playlist-buffer to the returned buffer."
+  (unwind-protect
+      (let ((result (cj/music--ensure-playlist-buffer)))
+        (should (eq emms-playlist-buffer result)))
+    (test-ensure--teardown)))
+
+(ert-deftest test-music-config--ensure-playlist-buffer-boundary-sets-buffer-local-flag ()
+  "Sets emms-playlist-buffer-p to t in the buffer."
+  (unwind-protect
+      (let ((result (cj/music--ensure-playlist-buffer)))
+        (with-current-buffer result
+          (should (eq emms-playlist-buffer-p t))))
+    (test-ensure--teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-music-config--ensure-playlist-buffer-error-killed-buffer-recreated ()
+  "After buffer is killed, calling again creates a new live buffer."
+  (unwind-protect
+      (progn
+        (let ((buf1 (cj/music--ensure-playlist-buffer)))
+          (kill-buffer buf1))
+        (let ((buf2 (cj/music--ensure-playlist-buffer)))
+          (should (buffer-live-p buf2))
+          (should (equal (buffer-name buf2) cj/music-playlist-buffer-name))))
+    (test-ensure--teardown)))
+
+(provide 'test-music-config--ensure-playlist-buffer)
+;;; test-music-config--ensure-playlist-buffer.el ends here
diff --git a/tests/test-music-config--header-text.el b/tests/test-music-config--header-text.el
new file mode 100644
index 00000000..8de97350
--- /dev/null
+++ b/tests/test-music-config--header-text.el
@@ -0,0 +1,156 @@
+;;; test-music-config--header-text.el --- Tests for playlist header string generation -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; Unit tests for cj/music--header-text function.
+;; Tests the multi-line header string builder for the playlist overlay.
+;;
+;; Test organization:
+;; - Normal Cases: Playlist name from file, "Untitled" default, track count
+;; - Boundary Cases: Stopped state, paused state, mode indicators
+;; - Error Cases: Empty playlist buffer
+;;
+;;; Code:
+
+(require 'ert)
+
+;; Stub missing dependencies before loading music-config
+(defvar-keymap cj/custom-keymap
+  :doc "Stub keymap for testing")
+
+;; Add EMMS elpa directory to load path for batch testing
+(let ((emms-dir (car (file-expand-wildcards
+                      (expand-file-name "elpa/emms-*" user-emacs-directory)))))
+  (when emms-dir
+    (add-to-list 'load-path emms-dir)))
+
+(require 'emms)
+(require 'emms-playlist-mode)
+(require 'music-config)
+
+;;; Test helpers
+
+(defun test-header--setup-playlist-buffer (track-names)
+  "Create an EMMS playlist buffer with TRACK-NAMES and return it."
+  (let ((buf (get-buffer-create cj/music-playlist-buffer-name)))
+    (with-current-buffer buf
+      (emms-playlist-mode)
+      (setq emms-playlist-buffer-p t)
+      (let ((inhibit-read-only t))
+        (erase-buffer)
+        (dolist (name track-names)
+          (emms-playlist-insert-track (emms-track 'file name)))))
+    (setq emms-playlist-buffer buf)
+    buf))
+
+(defun test-header--teardown ()
+  "Clean up test playlist buffer and reset EMMS state."
+  (setq emms-player-playing-p nil)
+  (setq emms-player-paused-p nil)
+  (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+    (with-current-buffer buf
+      (setq cj/music-playlist-file nil))
+    (kill-buffer buf)))
+
+(defun test-header--strip-properties (str)
+  "Return STR with all text properties removed."
+  (let ((s (copy-sequence str)))
+    (set-text-properties 0 (length s) nil s)
+    s))
+
+;;; Normal Cases
+
+(ert-deftest test-music-config--header-text-normal-shows-playlist-name-from-file ()
+  "Header shows playlist name derived from cj/music-playlist-file."
+  (unwind-protect
+      (progn
+        (test-header--setup-playlist-buffer '("/music/a.mp3"))
+        (with-current-buffer cj/music-playlist-buffer-name
+          (setq cj/music-playlist-file "/path/to/my-jazz.m3u"))
+        (let* ((header (with-current-buffer cj/music-playlist-buffer-name
+                         (cj/music--header-text)))
+               (plain (test-header--strip-properties header)))
+          (should (string-match-p "my-jazz" plain))))
+    (test-header--teardown)))
+
+(ert-deftest test-music-config--header-text-normal-shows-untitled-when-no-file ()
+  "Header shows 'Untitled' when no playlist file is associated."
+  (unwind-protect
+      (progn
+        (test-header--setup-playlist-buffer '("/music/a.mp3"))
+        (with-current-buffer cj/music-playlist-buffer-name
+          (setq cj/music-playlist-file nil))
+        (let* ((header (with-current-buffer cj/music-playlist-buffer-name
+                         (cj/music--header-text)))
+               (plain (test-header--strip-properties header)))
+          (should (string-match-p "Untitled" plain))))
+    (test-header--teardown)))
+
+(ert-deftest test-music-config--header-text-normal-shows-track-count ()
+  "Header shows correct track count."
+  (unwind-protect
+      (progn
+        (test-header--setup-playlist-buffer '("/music/a.mp3" "/music/b.mp3" "/music/c.mp3"))
+        (let* ((header (with-current-buffer cj/music-playlist-buffer-name
+                         (cj/music--header-text)))
+               (plain (test-header--strip-properties header)))
+          (should (string-match-p "(3)" plain))))
+    (test-header--teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-music-config--header-text-boundary-stopped-state ()
+  "Header shows 'Stopped' when not playing."
+  (unwind-protect
+      (progn
+        (test-header--setup-playlist-buffer '("/music/a.mp3"))
+        (setq emms-player-playing-p nil)
+        (let* ((header (with-current-buffer cj/music-playlist-buffer-name
+                         (cj/music--header-text)))
+               (plain (test-header--strip-properties header)))
+          (should (string-match-p "Stopped" plain))))
+    (test-header--teardown)))
+
+(ert-deftest test-music-config--header-text-boundary-paused-state ()
+  "Header shows 'Paused' when player is paused."
+  (unwind-protect
+      (progn
+        (test-header--setup-playlist-buffer '("/music/a.mp3"))
+        (setq emms-player-playing-p t)
+        (setq emms-player-paused-p t)
+        (let* ((header (with-current-buffer cj/music-playlist-buffer-name
+                         (cj/music--header-text)))
+               (plain (test-header--strip-properties header)))
+          (should (string-match-p "Paused" plain))))
+    (test-header--teardown)))
+
+(ert-deftest test-music-config--header-text-boundary-contains-mode-labels ()
+  "Header contains mode indicator labels for repeat, single, random, consume."
+  (unwind-protect
+      (progn
+        (test-header--setup-playlist-buffer '("/music/a.mp3"))
+        (let* ((header (with-current-buffer cj/music-playlist-buffer-name
+                         (cj/music--header-text)))
+               (plain (test-header--strip-properties header)))
+          (should (string-match-p "repeat" plain))
+          (should (string-match-p "single" plain))
+          (should (string-match-p "random" plain))
+          (should (string-match-p "consume" plain))))
+    (test-header--teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-music-config--header-text-error-empty-playlist-shows-zero-count ()
+  "Header shows (0) for empty playlist."
+  (unwind-protect
+      (progn
+        (test-header--setup-playlist-buffer '())
+        (let* ((header (with-current-buffer cj/music-playlist-buffer-name
+                         (cj/music--header-text)))
+               (plain (test-header--strip-properties header)))
+          (should (string-match-p "(0)" plain))))
+    (test-header--teardown)))
+
+(provide 'test-music-config--header-text)
+;;; test-music-config--header-text.el ends here
diff --git a/tests/test-music-config--playlist-modified-p.el b/tests/test-music-config--playlist-modified-p.el
new file mode 100644
index 00000000..cbfc71e3
--- /dev/null
+++ b/tests/test-music-config--playlist-modified-p.el
@@ -0,0 +1,145 @@
+;;; test-music-config--playlist-modified-p.el --- Tests for playlist modification detection -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; Unit tests for cj/music--playlist-modified-p function.
+;; Tests the logic that compares the current EMMS playlist buffer
+;; against its associated M3U file to detect unsaved changes.
+;;
+;; Test organization:
+;; - Normal Cases: Matching/differing track lists
+;; - Boundary Cases: Empty playlists, nil file, ordering
+;; - Error Cases: Missing M3U file, missing buffer
+;;
+;;; Code:
+
+(require 'ert)
+
+;; Stub missing dependencies before loading music-config
+(defvar-keymap cj/custom-keymap
+  :doc "Stub keymap for testing")
+
+;; Add EMMS elpa directory to load path for batch testing
+(let ((emms-dir (car (file-expand-wildcards
+                      (expand-file-name "elpa/emms-*" user-emacs-directory)))))
+  (when emms-dir
+    (add-to-list 'load-path emms-dir)))
+
+(require 'emms)
+(require 'emms-playlist-mode)
+(require 'music-config)
+
+;;; Test helpers
+
+(defun test-modified--setup-playlist-buffer (track-names)
+  "Create an EMMS playlist buffer with TRACK-NAMES and return it.
+Each entry in TRACK-NAMES becomes a file track in the playlist."
+  (let ((buf (get-buffer-create cj/music-playlist-buffer-name)))
+    (with-current-buffer buf
+      (emms-playlist-mode)
+      (setq emms-playlist-buffer-p t)
+      (let ((inhibit-read-only t))
+        (erase-buffer)
+        (dolist (name track-names)
+          (emms-playlist-insert-track (emms-track 'file name)))))
+    (setq emms-playlist-buffer buf)
+    buf))
+
+(defun test-modified--teardown ()
+  "Clean up test playlist buffer."
+  (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+    (kill-buffer buf)))
+
+;;; Normal Cases
+
+(ert-deftest test-music-config--playlist-modified-p-normal-identical-tracks-returns-nil ()
+  "Identical track lists in file and playlist returns nil (not modified)."
+  (unwind-protect
+      (let* ((tracks '("/music/a.mp3" "/music/b.mp3" "/music/c.mp3"))
+             (cj/music-playlist-file "/fake/playlist.m3u"))
+        (test-modified--setup-playlist-buffer tracks)
+        (cl-letf (((symbol-function 'cj/music--m3u-file-tracks)
+                   (lambda (_file) tracks)))
+          (should-not (cj/music--playlist-modified-p))))
+    (test-modified--teardown)))
+
+(ert-deftest test-music-config--playlist-modified-p-normal-different-tracks-returns-non-nil ()
+  "Different track lists returns non-nil (modified)."
+  (unwind-protect
+      (let* ((file-tracks '("/music/a.mp3" "/music/b.mp3"))
+             (buf-tracks '("/music/a.mp3" "/music/c.mp3"))
+             (cj/music-playlist-file "/fake/playlist.m3u"))
+        (test-modified--setup-playlist-buffer buf-tracks)
+        (cl-letf (((symbol-function 'cj/music--m3u-file-tracks)
+                   (lambda (_file) file-tracks)))
+          (should (cj/music--playlist-modified-p))))
+    (test-modified--teardown)))
+
+(ert-deftest test-music-config--playlist-modified-p-normal-extra-track-returns-non-nil ()
+  "Playlist with extra track compared to file returns non-nil."
+  (unwind-protect
+      (let* ((file-tracks '("/music/a.mp3" "/music/b.mp3"))
+             (buf-tracks '("/music/a.mp3" "/music/b.mp3" "/music/c.mp3"))
+             (cj/music-playlist-file "/fake/playlist.m3u"))
+        (test-modified--setup-playlist-buffer buf-tracks)
+        (cl-letf (((symbol-function 'cj/music--m3u-file-tracks)
+                   (lambda (_file) file-tracks)))
+          (should (cj/music--playlist-modified-p))))
+    (test-modified--teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-music-config--playlist-modified-p-boundary-no-playlist-file-returns-nil ()
+  "Nil cj/music-playlist-file returns nil without comparing tracks."
+  (unwind-protect
+      (let ((cj/music-playlist-file nil))
+        (test-modified--setup-playlist-buffer '("/music/a.mp3"))
+        (should-not (cj/music--playlist-modified-p)))
+    (test-modified--teardown)))
+
+(ert-deftest test-music-config--playlist-modified-p-boundary-empty-file-and-playlist-returns-nil ()
+  "Both empty file tracks and empty playlist returns nil."
+  (unwind-protect
+      (let ((cj/music-playlist-file "/fake/playlist.m3u"))
+        (test-modified--setup-playlist-buffer '())
+        (cl-letf (((symbol-function 'cj/music--m3u-file-tracks)
+                   (lambda (_file) nil)))
+          (should-not (cj/music--playlist-modified-p))))
+    (test-modified--teardown)))
+
+(ert-deftest test-music-config--playlist-modified-p-boundary-order-difference-returns-non-nil ()
+  "Same tracks in different order returns non-nil."
+  (unwind-protect
+      (let* ((file-tracks '("/music/a.mp3" "/music/b.mp3"))
+             (buf-tracks '("/music/b.mp3" "/music/a.mp3"))
+             (cj/music-playlist-file "/fake/playlist.m3u"))
+        (test-modified--setup-playlist-buffer buf-tracks)
+        (cl-letf (((symbol-function 'cj/music--m3u-file-tracks)
+                   (lambda (_file) file-tracks)))
+          (should (cj/music--playlist-modified-p))))
+    (test-modified--teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-music-config--playlist-modified-p-error-missing-m3u-file-returns-nil ()
+  "When M3U file doesn't exist, m3u-file-tracks returns nil; empty playlist matches."
+  (unwind-protect
+      (let ((cj/music-playlist-file "/nonexistent/playlist.m3u"))
+        (test-modified--setup-playlist-buffer '())
+        ;; cj/music--m3u-file-tracks returns nil for nonexistent files
+        ;; empty playlist also returns nil, so equal = not modified
+        (should-not (cj/music--playlist-modified-p)))
+    (test-modified--teardown)))
+
+(ert-deftest test-music-config--playlist-modified-p-error-missing-m3u-with-tracks-returns-non-nil ()
+  "When M3U file doesn't exist but playlist has tracks, returns non-nil."
+  (unwind-protect
+      (let ((cj/music-playlist-file "/nonexistent/playlist.m3u"))
+        (test-modified--setup-playlist-buffer '("/music/a.mp3"))
+        ;; m3u-file-tracks returns nil, but playlist has tracks = modified
+        (should (cj/music--playlist-modified-p)))
+    (test-modified--teardown)))
+
+(provide 'test-music-config--playlist-modified-p)
+;;; test-music-config--playlist-modified-p.el ends here
diff --git a/tests/test-music-config--playlist-tracks.el b/tests/test-music-config--playlist-tracks.el
new file mode 100644
index 00000000..7736b8d2
--- /dev/null
+++ b/tests/test-music-config--playlist-tracks.el
@@ -0,0 +1,123 @@
+;;; test-music-config--playlist-tracks.el --- Tests for playlist track extraction -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; Unit tests for cj/music--playlist-tracks function.
+;; Tests reading track names from the current EMMS playlist buffer.
+;;
+;; Test organization:
+;; - Normal Cases: Single and multiple tracks
+;; - Boundary Cases: Empty playlist, order preservation
+;; - Error Cases: No playlist buffer, tracks without names
+;;
+;;; Code:
+
+(require 'ert)
+
+;; Stub missing dependencies before loading music-config
+(defvar-keymap cj/custom-keymap
+  :doc "Stub keymap for testing")
+
+;; Add EMMS elpa directory to load path for batch testing
+(let ((emms-dir (car (file-expand-wildcards
+                      (expand-file-name "elpa/emms-*" user-emacs-directory)))))
+  (when emms-dir
+    (add-to-list 'load-path emms-dir)))
+
+(require 'emms)
+(require 'emms-playlist-mode)
+(require 'music-config)
+
+;;; Test helpers
+
+(defun test-tracks--setup-playlist-buffer (track-names)
+  "Create an EMMS playlist buffer with TRACK-NAMES and return it.
+Each entry in TRACK-NAMES becomes a file track in the playlist."
+  (let ((buf (get-buffer-create cj/music-playlist-buffer-name)))
+    (with-current-buffer buf
+      (emms-playlist-mode)
+      (setq emms-playlist-buffer-p t)
+      (let ((inhibit-read-only t))
+        (erase-buffer)
+        (dolist (name track-names)
+          (emms-playlist-insert-track (emms-track 'file name)))))
+    (setq emms-playlist-buffer buf)
+    buf))
+
+(defun test-tracks--teardown ()
+  "Clean up test playlist buffer."
+  (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+    (kill-buffer buf)))
+
+;;; Normal Cases
+
+(ert-deftest test-music-config--playlist-tracks-normal-multiple-tracks-returns-list ()
+  "Multiple tracks in playlist returns list of track names."
+  (unwind-protect
+      (let ((tracks '("/music/a.mp3" "/music/b.mp3" "/music/c.mp3")))
+        (test-tracks--setup-playlist-buffer tracks)
+        (should (equal (cj/music--playlist-tracks) tracks)))
+    (test-tracks--teardown)))
+
+(ert-deftest test-music-config--playlist-tracks-normal-single-track-returns-list ()
+  "Single track in playlist returns single-element list."
+  (unwind-protect
+      (let ((tracks '("/music/only.mp3")))
+        (test-tracks--setup-playlist-buffer tracks)
+        (should (equal (cj/music--playlist-tracks) tracks)))
+    (test-tracks--teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-music-config--playlist-tracks-boundary-empty-playlist-returns-nil ()
+  "Empty playlist returns nil (empty list)."
+  (unwind-protect
+      (progn
+        (test-tracks--setup-playlist-buffer '())
+        (should-not (cj/music--playlist-tracks)))
+    (test-tracks--teardown)))
+
+(ert-deftest test-music-config--playlist-tracks-boundary-preserves-insertion-order ()
+  "Track order matches insertion order."
+  (unwind-protect
+      (let ((tracks '("/music/z.mp3" "/music/a.mp3" "/music/m.mp3")))
+        (test-tracks--setup-playlist-buffer tracks)
+        (should (equal (cj/music--playlist-tracks) tracks)))
+    (test-tracks--teardown)))
+
+(ert-deftest test-music-config--playlist-tracks-boundary-url-tracks-included ()
+  "URL tracks are included alongside file tracks."
+  (unwind-protect
+      (let* ((buf (get-buffer-create cj/music-playlist-buffer-name)))
+        (with-current-buffer buf
+          (emms-playlist-mode)
+          (setq emms-playlist-buffer-p t)
+          (let ((inhibit-read-only t))
+            (erase-buffer)
+            (emms-playlist-insert-track (emms-track 'file "/music/local.mp3"))
+            (emms-playlist-insert-track (emms-track 'url "http://stream.example.com/radio"))))
+        (setq emms-playlist-buffer buf)
+        (let ((result (cj/music--playlist-tracks)))
+          (should (= 2 (length result)))
+          (should (equal (nth 0 result) "/music/local.mp3"))
+          (should (equal (nth 1 result) "http://stream.example.com/radio"))))
+    (test-tracks--teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-music-config--playlist-tracks-error-no-buffer-creates-one ()
+  "When playlist buffer doesn't exist, ensure-playlist-buffer creates it."
+  (unwind-protect
+      (progn
+        ;; Kill any existing buffer
+        (when-let ((buf (get-buffer cj/music-playlist-buffer-name)))
+          (kill-buffer buf))
+        ;; Should create buffer and return empty list
+        (should-not (cj/music--playlist-tracks))
+        ;; Buffer should now exist
+        (should (get-buffer cj/music-playlist-buffer-name)))
+    (test-tracks--teardown)))
+
+(provide 'test-music-config--playlist-tracks)
+;;; test-music-config--playlist-tracks.el ends here
diff --git a/tests/test-music-config-create-radio-station.el b/tests/test-music-config-create-radio-station.el
new file mode 100644
index 00000000..1f4365a4
--- /dev/null
+++ b/tests/test-music-config-create-radio-station.el
@@ -0,0 +1,153 @@
+;;; test-music-config-create-radio-station.el --- Tests for radio station creation -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; Unit tests for cj/music-create-radio-station function.
+;; Tests M3U file creation for radio stations with stream URLs.
+;;
+;; Test organization:
+;; - Normal Cases: Standard creation, EXTM3U format, safe filename
+;; - Boundary Cases: Unicode name, complex URL, overwrite confirmed
+;; - Error Cases: Empty name, empty URL, overwrite declined
+;;
+;;; Code:
+
+(require 'ert)
+(require 'testutil-general)
+
+;; Stub missing dependencies before loading music-config
+(defvar-keymap cj/custom-keymap
+  :doc "Stub keymap for testing")
+
+;; Load production code
+(require 'music-config)
+
+;;; Setup & Teardown
+
+(defun test-music-config-create-radio-station-setup ()
+  "Setup test environment with temp directory for M3U output."
+  (cj/create-test-base-dir)
+  (cj/create-test-subdirectory "radio-playlists"))
+
+(defun test-music-config-create-radio-station-teardown ()
+  "Clean up test environment."
+  (cj/delete-test-base-dir))
+
+;;; Normal Cases
+
+(ert-deftest test-music-config-create-radio-station-normal-creates-m3u-file ()
+  "Creating a radio station produces an M3U file in the music root."
+  (let ((test-dir (test-music-config-create-radio-station-setup)))
+    (unwind-protect
+        (let ((cj/music-m3u-root test-dir))
+          (cj/music-create-radio-station "Jazz FM" "http://stream.jazzfm.com/radio")
+          (let ((expected-file (expand-file-name "Jazz_FM_Radio.m3u" test-dir)))
+            (should (file-exists-p expected-file))))
+      (test-music-config-create-radio-station-teardown))))
+
+(ert-deftest test-music-config-create-radio-station-normal-extm3u-format ()
+  "Created file contains EXTM3U header, EXTINF with station name, and URL."
+  (let ((test-dir (test-music-config-create-radio-station-setup)))
+    (unwind-protect
+        (let ((cj/music-m3u-root test-dir))
+          (cj/music-create-radio-station "Jazz FM" "http://stream.jazzfm.com/radio")
+          (let ((content (with-temp-buffer
+                           (insert-file-contents
+                            (expand-file-name "Jazz_FM_Radio.m3u" test-dir))
+                           (buffer-string))))
+            (should (string-match-p "^#EXTM3U" content))
+            (should (string-match-p "#EXTINF:-1,Jazz FM" content))
+            (should (string-match-p "http://stream.jazzfm.com/radio" content))))
+      (test-music-config-create-radio-station-teardown))))
+
+(ert-deftest test-music-config-create-radio-station-normal-safe-filename ()
+  "Station name with special characters produces filesystem-safe filename."
+  (let ((test-dir (test-music-config-create-radio-station-setup)))
+    (unwind-protect
+        (let ((cj/music-m3u-root test-dir))
+          (cj/music-create-radio-station "Rock & Roll 101.5" "http://example.com/stream")
+          ;; Spaces and special chars replaced with underscores
+          (let ((expected-file (expand-file-name "Rock___Roll_101_5_Radio.m3u" test-dir)))
+            (should (file-exists-p expected-file))))
+      (test-music-config-create-radio-station-teardown))))
+
+;;; Boundary Cases
+
+(ert-deftest test-music-config-create-radio-station-boundary-unicode-name-safe-filename ()
+  "Unicode station name produces safe filename while preserving name in EXTINF."
+  (let ((test-dir (test-music-config-create-radio-station-setup)))
+    (unwind-protect
+        (let ((cj/music-m3u-root test-dir))
+          (cj/music-create-radio-station "Klassik Radio" "http://example.com/stream")
+          ;; Name is all ASCII-safe, so filename uses it directly
+          (should (file-exists-p (expand-file-name "Klassik_Radio_Radio.m3u" test-dir)))
+          ;; Original name preserved in EXTINF inside the file
+          (let ((content (with-temp-buffer
+                           (insert-file-contents
+                            (expand-file-name "Klassik_Radio_Radio.m3u" test-dir))
+                           (buffer-string))))
+            (should (string-match-p "Klassik Radio" content))))
+      (test-music-config-create-radio-station-teardown))))
+
+(ert-deftest test-music-config-create-radio-station-boundary-url-with-query-params ()
+  "Complex URL with query parameters preserved in file content."
+  (let ((test-dir (test-music-config-create-radio-station-setup)))
+    (unwind-protect
+        (let ((cj/music-m3u-root test-dir)
+              (url "https://stream.example.com/radio?format=mp3&quality=320&token=abc123"))
+          (cj/music-create-radio-station "Test Radio" url)
+          (let ((content (with-temp-buffer
+                           (insert-file-contents
+                            (expand-file-name "Test_Radio_Radio.m3u" test-dir))
+                           (buffer-string))))
+            (should (string-match-p (regexp-quote url) content))))
+      (test-music-config-create-radio-station-teardown))))
+
+(ert-deftest test-music-config-create-radio-station-boundary-overwrite-confirmed ()
+  "Overwriting existing file when user confirms succeeds."
+  (let ((test-dir (test-music-config-create-radio-station-setup)))
+    (unwind-protect
+        (let ((cj/music-m3u-root test-dir))
+          ;; Create initial file
+          (cj/music-create-radio-station "MyRadio" "http://old.url/stream")
+          (let ((file (expand-file-name "MyRadio_Radio.m3u" test-dir)))
+            (should (file-exists-p file))
+            ;; Overwrite with user confirming
+            (cl-letf (((symbol-function 'yes-or-no-p) (lambda (_prompt) t)))
+              (cj/music-create-radio-station "MyRadio" "http://new.url/stream"))
+            ;; File should now contain new URL
+            (let ((content (with-temp-buffer
+                             (insert-file-contents file)
+                             (buffer-string))))
+              (should (string-match-p "http://new.url/stream" content))
+              (should-not (string-match-p "http://old.url/stream" content)))))
+      (test-music-config-create-radio-station-teardown))))
+
+;;; Error Cases
+
+(ert-deftest test-music-config-create-radio-station-error-empty-name-signals-user-error ()
+  "Empty station name signals user-error."
+  (should-error (cj/music-create-radio-station "" "http://example.com/stream")
+                :type 'user-error))
+
+(ert-deftest test-music-config-create-radio-station-error-empty-url-signals-user-error ()
+  "Empty URL signals user-error."
+  (should-error (cj/music-create-radio-station "Test Radio" "")
+                :type 'user-error))
+
+(ert-deftest test-music-config-create-radio-station-error-overwrite-declined-signals-user-error ()
+  "Declining overwrite signals user-error."
+  (let ((test-dir (test-music-config-create-radio-station-setup)))
+    (unwind-protect
+        (let ((cj/music-m3u-root test-dir))
+          ;; Create initial file
+          (cj/music-create-radio-station "MyRadio" "http://old.url/stream")
+          ;; Decline overwrite
+          (cl-letf (((symbol-function 'yes-or-no-p) (lambda (_prompt) nil)))
+            (should-error (cj/music-create-radio-station "MyRadio" "http://new.url/stream")
+                          :type 'user-error)))
+      (test-music-config-create-radio-station-teardown))))
+
+(provide 'test-music-config-create-radio-station)
+;;; test-music-config-create-radio-station.el ends here