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, 180 insertions, 0 deletions

diff --git a/tests/test-calendar-sync--expand-daily.el b/tests/test-calendar-sync--expand-daily.el
new file mode 100644
index 00000000..43b93664
--- /dev/null
+++ b/tests/test-calendar-sync--expand-daily.el
@@ -0,0 +1,180 @@
+;;; test-calendar-sync--expand-daily.el --- Tests for calendar-sync--expand-daily  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Characterization tests for calendar-sync--expand-daily.
+;; 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-daily-normal-generates-occurrences ()
+  "Test expanding daily event generates occurrences within range."
+  (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 "Daily Standup"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'daily :interval 1))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    ;; ~365 days future + ~90 days past = ~456 days of occurrences
+    (should (> (length occurrences) 300))
+    (should (< (length occurrences) 500))))
+
+(ert-deftest test-calendar-sync--expand-daily-normal-preserves-time ()
+  "Test that each occurrence preserves the original event time."
+  (let* ((start-date (test-calendar-sync-time-days-from-now 1 14 30))
+         (end-date (test-calendar-sync-time-days-from-now 1 15 30))
+         (base-event (list :summary "Afternoon Check"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'daily :interval 1))
+         (range (test-calendar-sync-narrow-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    (should (> (length occurrences) 0))
+    (dolist (occ occurrences)
+      (let ((s (plist-get occ :start)))
+        (should (= (nth 3 s) 14))
+        (should (= (nth 4 s) 30))))))
+
+(ert-deftest test-calendar-sync--expand-daily-normal-interval-two ()
+  "Test expanding every-other-day event."
+  (let* ((start-date (test-calendar-sync-time-days-from-now 1 9 0))
+         (end-date (test-calendar-sync-time-days-from-now 1 10 0))
+         (base-event (list :summary "Every Other Day"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'daily :interval 2))
+         (range (test-calendar-sync-narrow-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    ;; 30 days / 2 = ~15 occurrences
+    (should (>= (length occurrences) 12))
+    (should (<= (length occurrences) 18))))
+
+(ert-deftest test-calendar-sync--expand-daily-normal-consecutive-dates-increase ()
+  "Test that occurrences are on consecutive dates spaced by interval."
+  (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 "Daily"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'daily :interval 3))
+         (range (test-calendar-sync-narrow-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    (when (> (length occurrences) 1)
+      (let ((prev (plist-get (car occurrences) :start)))
+        (dolist (occ (cdr occurrences))
+          (let ((curr (plist-get occ :start)))
+            ;; Days between consecutive occurrences should be ~3
+            (let ((days (test-calendar-sync-days-between prev curr)))
+              (should (>= days 2.5))
+              (should (<= days 3.5)))
+            (setq prev curr)))))))
+
+;;; Boundary Cases
+
+(ert-deftest test-calendar-sync--expand-daily-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 'daily :interval 1 :count 7))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    (should (= (length occurrences) 7))))
+
+(ert-deftest test-calendar-sync--expand-daily-boundary-until-limits-occurrences ()
+  "Test that UNTIL date stops expansion."
+  (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))
+         (until-date (test-calendar-sync-time-date-only 15))
+         (base-event (list :summary "Until-Limited"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'daily :interval 1 :until until-date))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    ;; ~14 days worth of daily occurrences
+    (should (>= (length occurrences) 12))
+    (should (<= (length occurrences) 16))))
+
+(ert-deftest test-calendar-sync--expand-daily-boundary-respects-date-range ()
+  "Test that occurrences are within or at the date range boundaries."
+  (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 "Ranged"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'daily :interval 1))
+         (range (test-calendar-sync-narrow-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range))
+         (range-start (nth 0 range))
+         ;; Add 1 day buffer — date-in-range-p checks date portion only
+         (range-end-padded (time-add (nth 1 range) 86400)))
+    (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-padded))))))
+
+(ert-deftest test-calendar-sync--expand-daily-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 'daily :interval 1 :count 1))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    (should (= (length occurrences) 1))))
+
+(ert-deftest test-calendar-sync--expand-daily-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 "My Event"
+                           :start start-date
+                           :end end-date
+                           :location "Room 5"))
+         (rrule (list :freq 'daily :interval 1 :count 3))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    (dolist (occ occurrences)
+      (should (equal (plist-get occ :summary) "My Event")))))
+
+;;; Error Cases
+
+(ert-deftest test-calendar-sync--expand-daily-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 100 10 0))
+         (end-date (test-calendar-sync-time-days-ago 100 11 0))
+         (until-date (test-calendar-sync-time-date-only-ago 50))
+         (base-event (list :summary "Past"
+                           :start start-date
+                           :end end-date))
+         (rrule (list :freq 'daily :interval 1 :until until-date))
+         (range (list (time-subtract (current-time) (* 30 86400))
+                      (time-add (current-time) (* 365 86400))))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    (should (= (length occurrences) 0))))
+
+(ert-deftest test-calendar-sync--expand-daily-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 'daily :interval 1 :count 5))
+         (range (test-calendar-sync-wide-range))
+         (occurrences (calendar-sync--expand-daily base-event rrule range)))
+    (should (= (length occurrences) 5))))
+
+(provide 'test-calendar-sync--expand-daily)
+;;; test-calendar-sync--expand-daily.el ends here