feat(music): add random-aware next/previous; refactor music + calendar-syncHEADmain

Music: random mode now respected by next/previous keys. Previous navigates
a 50-track play history ring buffer. Fixed playlist replacement bug.
24 new tests.

Calendar-sync: consolidated duplicate parse functions, extracted timezone
localization helper, unified expand-daily/monthly/yearly into parameterized
function, removed dead code. 33 new characterization tests. -90 lines.

1 files changed, 179 insertions, 0 deletions

diff --git a/tests/test-calendar-sync--expand-yearly.el b/tests/test-calendar-sync--expand-yearly.el
new file mode 100644
index 00000000..ad9b8f27
--- /dev/null
+++ b/tests/test-calendar-sync--expand-yearly.el
@@ -0,0 +1,179 @@
+;;; test-calendar-sync--expand-yearly.el --- Tests for calendar-sync--expand-yearly  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Characterization tests for calendar-sync--expand-yearly.
+;; Captures current behavior before refactoring into unified expand function.
+;; Uses dynamic timestamps to avoid hardcoded dates.
+
+;;; Code:
+
+(require 'ert)
+(require 'testutil-calendar-sync)
+(require 'calendar-sync)
+
+;;; Normal Cases
+
+(ert-deftest test-calendar-sync--expand-yearly-normal-generates-occurrences ()
+  "Test expanding yearly event generates occurrences within range."
+  (let* ((start-date (test-calendar-sync-time-days-ago 800 10 0))
+         (end-date (test-calendar-sync-time-days-ago 800 11 0))
+         (base-event (list :summary "Birthday"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    ;; Range covers ~1.25 years, event started ~2.2 years ago
+    ;; Should see 1-2 occurrences in range
+    (should (>= (length occurrences) 1))
+    (should (<= (length occurrences) 3))))
+
+(ert-deftest test-calendar-sync--expand-yearly-normal-preserves-date ()
+  "Test that each occurrence falls on the same month and day."
+  (let* ((start-date (test-calendar-sync-time-days-ago 1100 10 0))
+         (end-date (test-calendar-sync-time-days-ago 1100 11 0))
+         (expected-month (nth 1 start-date))
+         (expected-day (nth 2 start-date))
+         (base-event (list :summary "Anniversary"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    (should (> (length occurrences) 0))
+    (dolist (occ occurrences)
+      (let ((s (plist-get occ :start)))
+        (should (= (nth 1 s) expected-month))
+        (should (= (nth 2 s) expected-day))))))
+
+(ert-deftest test-calendar-sync--expand-yearly-normal-preserves-time ()
+  "Test that each occurrence preserves the original event time."
+  (let* ((start-date (test-calendar-sync-time-days-ago 400 15 30))
+         (end-date (test-calendar-sync-time-days-ago 400 16 30))
+         (base-event (list :summary "Yearly"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1 :count 5))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    (dolist (occ occurrences)
+      (let ((s (plist-get occ :start)))
+        (should (= (nth 3 s) 15))
+        (should (= (nth 4 s) 30))))))
+
+(ert-deftest test-calendar-sync--expand-yearly-normal-interval-two ()
+  "Test expanding bi-yearly event."
+  (let* ((start-date (test-calendar-sync-time-days-ago 2000 10 0))
+         (end-date (test-calendar-sync-time-days-ago 2000 11 0))
+         (base-event (list :summary "Bi-Yearly"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 2))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    ;; Over ~5.5 years, bi-yearly = ~2-3 total, 0-1 in range
+    (should (<= (length occurrences) 2))))
+
+;;; Boundary Cases
+
+(ert-deftest test-calendar-sync--expand-yearly-boundary-count-limits-occurrences ()
+  "Test that COUNT limits the total number of occurrences."
+  (let* ((start-date (test-calendar-sync-time-days-from-now 1 10 0))
+         (end-date (test-calendar-sync-time-days-from-now 1 11 0))
+         (base-event (list :summary "Limited"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1 :count 3))
+         ;; Use a very wide range to capture all 3 years
+         (range (list (time-subtract (current-time) (* 90 86400))
+                      (time-add (current-time) (* 1460 86400))))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    (should (= (length occurrences) 3))))
+
+(ert-deftest test-calendar-sync--expand-yearly-boundary-until-limits-occurrences ()
+  "Test that UNTIL date stops expansion."
+  (let* ((start-date (test-calendar-sync-time-days-ago 1000 10 0))
+         (end-date (test-calendar-sync-time-days-ago 1000 11 0))
+         (until-date (test-calendar-sync-time-date-only 365))
+         (base-event (list :summary "Until-Limited"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1 :until until-date))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    ;; Should have occurrences within range but stopped by UNTIL
+    (should (>= (length occurrences) 1))
+    (should (<= (length occurrences) 3))))
+
+(ert-deftest test-calendar-sync--expand-yearly-boundary-count-one-returns-single ()
+  "Test that COUNT=1 returns exactly one occurrence."
+  (let* ((start-date (test-calendar-sync-time-days-from-now 1 10 0))
+         (end-date (test-calendar-sync-time-days-from-now 1 11 0))
+         (base-event (list :summary "Once"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1 :count 1))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    (should (= (length occurrences) 1))))
+
+(ert-deftest test-calendar-sync--expand-yearly-boundary-respects-date-range ()
+  "Test that occurrences outside date range are excluded."
+  (let* ((start-date (test-calendar-sync-time-days-ago 1500 10 0))
+         (end-date (test-calendar-sync-time-days-ago 1500 11 0))
+         (base-event (list :summary "Ranged"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1))
+         (range (test-calendar-sync-narrow-range))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range))
+         (range-start (nth 0 range))
+         (range-end (nth 1 range)))
+    (dolist (occ occurrences)
+      (let* ((s (plist-get occ :start))
+             (occ-time (test-calendar-sync-date-to-time-value s)))
+        (should (time-less-p range-start occ-time))
+        (should (time-less-p occ-time range-end))))))
+
+(ert-deftest test-calendar-sync--expand-yearly-boundary-preserves-summary ()
+  "Test that each occurrence carries the original summary."
+  (let* ((start-date (test-calendar-sync-time-days-from-now 1 10 0))
+         (end-date (test-calendar-sync-time-days-from-now 1 11 0))
+         (base-event (list :summary "Annual Gala"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1 :count 2))
+         (range (list (time-subtract (current-time) (* 90 86400))
+                      (time-add (current-time) (* 1460 86400))))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    (dolist (occ occurrences)
+      (should (equal (plist-get occ :summary) "Annual Gala")))))
+
+;;; Error Cases
+
+(ert-deftest test-calendar-sync--expand-yearly-error-past-until-returns-empty ()
+  "Test that UNTIL in the past produces no occurrences in future range."
+  (let* ((start-date (test-calendar-sync-time-days-ago 1500 10 0))
+         (end-date (test-calendar-sync-time-days-ago 1500 11 0))
+         (until-date (test-calendar-sync-time-date-only-ago 365))
+         (base-event (list :summary "Past"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'yearly :interval 1 :until until-date))
+         (range (list (time-subtract (current-time) (* 30 86400))
+                      (time-add (current-time) (* 365 86400))))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    (should (= (length occurrences) 0))))
+
+(ert-deftest test-calendar-sync--expand-yearly-error-no-end-time-still-works ()
+  "Test that event without :end still generates occurrences."
+  (let* ((start-date (test-calendar-sync-time-days-from-now 1 10 0))
+         (base-event (list :summary "No End" :start start-date))
+         (rrule (list :freq 'yearly :interval 1 :count 2))
+         (range (list (time-subtract (current-time) (* 90 86400))
+                      (time-add (current-time) (* 1460 86400))))
+         (occurrences (calendar-sync--expand-yearly base-event rrule range)))
+    (should (= (length occurrences) 2))))
+
+(provide 'test-calendar-sync--expand-yearly)
+;;; test-calendar-sync--expand-yearly.el ends here