feat(music): source M3U playlists from multiple directories

The MPD radio-stream playlists moved into version control at ~/.local/share/mpd/playlists/, while the 24 local-library playlists stay at ~/music/. MPD has a single playlist_directory and its load only sees that one, so the union has to happen at the Emacs layer.

I added cj/music-m3u-roots, a precedence-ordered list of directories the reading path unions (get-m3u-files, basenames, select, load). Missing directories are skipped. On a basename collision the earlier root wins, so a local playlist shadows a same-named radio one. Saving and radio-station creation still target the single cj/music-m3u-root. Radio .m3u hold stream URLs, which the track reader and the mpv subprocess already handle, so nothing else changed to play them.

The two tests that pinned the old single-directory contract now bind the list. Their "missing directory signals an error" cases became "missing directory is skipped" to match the new behavior.

1 files changed, 97 insertions, 0 deletions

diff --git a/tests/test-music-config--m3u-roots.el b/tests/test-music-config--m3u-roots.el
new file mode 100644
index 00000000..626415b6
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+++ b/tests/test-music-config--m3u-roots.el
@@ -0,0 +1,97 @@
+;;; test-music-config--m3u-roots.el --- multi-directory M3U sourcing tests -*- coding: utf-8; lexical-binding: t; -*-
+;;
+;; Author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;; The player sources .m3u playlists from a LIST of directories
+;; (`cj/music-m3u-roots') so the local-library playlists (~/music) and the
+;; dotfiles-tracked internet-radio playlists (MPD's playlist_directory) surface
+;; together for selection and loading.  Two pieces are tested:
+;;
+;; - `cj/music--dedup-m3u-files' — pure: turns a flat list of paths into
+;;   (BASENAME . PATH) conses, first occurrence of a basename winning.
+;; - `cj/music--get-m3u-files' — unions the roots on disk, skips missing dirs,
+;;   and applies the dedup so an earlier root shadows a same-named later one.
+;;
+;;; Code:
+
+(require 'ert)
+
+;; Stub missing dependencies before loading music-config.
+(defvar-keymap cj/custom-keymap
+  :doc "Stub keymap for testing")
+
+(require 'music-config)
+
+(declare-function cj/music--dedup-m3u-files "music-config" (paths))
+(declare-function cj/music--get-m3u-files "music-config" ())
+(defvar cj/music-m3u-roots)
+
+;;; --------------------------- cj/music--dedup-m3u-files ----------------------
+
+(ert-deftest test-music-config-dedup-m3u-distinct ()
+  "Normal: distinct basenames across dirs all appear, in order."
+  (should (equal (cj/music--dedup-m3u-files
+                  '("/music/rhcp.m3u" "/radio/90s Sounds.m3u"))
+                 '(("rhcp.m3u" . "/music/rhcp.m3u")
+                   ("90s Sounds.m3u" . "/radio/90s Sounds.m3u")))))
+
+(ert-deftest test-music-config-dedup-m3u-single ()
+  "Normal: a single path yields a single cons."
+  (should (equal (cj/music--dedup-m3u-files '("/music/blues.m3u"))
+                 '(("blues.m3u" . "/music/blues.m3u")))))
+
+(ert-deftest test-music-config-dedup-m3u-collision-first-wins ()
+  "Boundary: a basename in two dirs keeps the first path (earlier root wins)."
+  (should (equal (cj/music--dedup-m3u-files
+                  '("/music/jazz.m3u" "/radio/jazz.m3u"))
+                 '(("jazz.m3u" . "/music/jazz.m3u")))))
+
+(ert-deftest test-music-config-dedup-m3u-empty ()
+  "Boundary: an empty path list yields nil."
+  (should-not (cj/music--dedup-m3u-files '())))
+
+;;; ---------------------------- cj/music--get-m3u-files -----------------------
+
+(ert-deftest test-music-config-get-m3u-unions-roots ()
+  "Normal: M3Us from every existing root are unioned."
+  (let ((a (make-temp-file "m3u-a-" t))
+        (b (make-temp-file "m3u-b-" t)))
+    (unwind-protect
+        (progn
+          (write-region "" nil (expand-file-name "local.m3u" a))
+          (write-region "" nil (expand-file-name "radio.m3u" b))
+          (let* ((cj/music-m3u-roots (list a b))
+                 (bases (mapcar #'car (cj/music--get-m3u-files))))
+            (should (member "local.m3u" bases))
+            (should (member "radio.m3u" bases))))
+      (delete-directory a t)
+      (delete-directory b t))))
+
+(ert-deftest test-music-config-get-m3u-skips-missing-root ()
+  "Error: a non-existent directory in the list is skipped, not fatal."
+  (let ((a (make-temp-file "m3u-a-" t)))
+    (unwind-protect
+        (progn
+          (write-region "" nil (expand-file-name "local.m3u" a))
+          (let* ((cj/music-m3u-roots (list a "/no/such/dir/here"))
+                 (bases (mapcar #'car (cj/music--get-m3u-files))))
+            (should (equal bases '("local.m3u")))))
+      (delete-directory a t))))
+
+(ert-deftest test-music-config-get-m3u-collision-first-root-wins ()
+  "Boundary: same basename in two roots resolves to the earlier root's file."
+  (let ((a (make-temp-file "m3u-a-" t))
+        (b (make-temp-file "m3u-b-" t)))
+    (unwind-protect
+        (progn
+          (write-region "" nil (expand-file-name "jazz.m3u" a))
+          (write-region "" nil (expand-file-name "jazz.m3u" b))
+          (let* ((cj/music-m3u-roots (list a b))
+                 (pair (assoc "jazz.m3u" (cj/music--get-m3u-files))))
+            (should (string-prefix-p a (cdr pair)))))
+      (delete-directory a t)
+      (delete-directory b t))))
+
+(provide 'test-music-config--m3u-roots)
+;;; test-music-config--m3u-roots.el ends here