fix(calendar-sync): honor BYDAY rules and drop cancelled events

The expander ignored BYDAY on monthly and yearly rules and stepped DTSTART's day-of-month instead, so a "2nd Wednesday" series rendered on the 12th of every month, the wrong weekday most months. It now resolves nth-weekday entries (2WE, -1TU), bare weekdays with BYSETPOS, and yearly BYMONTH+BYDAY, so each occurrence lands on the day the rule names.

Nothing read the VEVENT STATUS property, so cancelled events rendered as normal meetings: a cancelled instance of a series reappeared at its original time, and standalone cancelled events stayed on the agenda. parse-event now drops STATUS:CANCELLED events, which also kills cancelled series masters. A cancelled RECURRENCE-ID override removes its occurrence instead of overriding it.

The fixes are coupled: until BYDAY generates the right dates, a cancelled override can't match the occurrence it removes.

1 files changed, 41 insertions, 0 deletions

diff --git a/tests/test-calendar-sync--parse-byday-entry.el b/tests/test-calendar-sync--parse-byday-entry.el
new file mode 100644
index 00000000..4a9b4ef5
--- /dev/null
+++ b/tests/test-calendar-sync--parse-byday-entry.el
@@ -0,0 +1,41 @@
+;;; test-calendar-sync--parse-byday-entry.el --- Tests for calendar-sync--parse-byday-entry  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for parsing a single RRULE BYDAY entry ("2WE", "-1TU", "SU") into
+;; an (ordinal . weekday-number) cons.  Ordinal is nil for a bare weekday.
+
+;;; Code:
+
+(require 'ert)
+(require 'calendar-sync)
+
+;;; Normal Cases
+
+(ert-deftest test-calendar-sync--parse-byday-entry-normal-positive-ordinal ()
+  "Normal: \"2WE\" parses to ordinal 2, Wednesday (3)."
+  (should (equal (calendar-sync--parse-byday-entry "2WE") '(2 . 3))))
+
+(ert-deftest test-calendar-sync--parse-byday-entry-normal-negative-ordinal ()
+  "Normal: \"-1TU\" parses to ordinal -1, Tuesday (2)."
+  (should (equal (calendar-sync--parse-byday-entry "-1TU") '(-1 . 2))))
+
+(ert-deftest test-calendar-sync--parse-byday-entry-normal-bare-weekday ()
+  "Normal: \"SU\" parses to nil ordinal, Sunday (7)."
+  (should (equal (calendar-sync--parse-byday-entry "SU") '(nil . 7))))
+
+;;; Boundary Cases
+
+(ert-deftest test-calendar-sync--parse-byday-entry-boundary-double-digit-ordinal ()
+  "Boundary: \"53MO\" (yearly-scale ordinal) parses without truncation."
+  (should (equal (calendar-sync--parse-byday-entry "53MO") '(53 . 1))))
+
+;;; Error Cases
+
+(ert-deftest test-calendar-sync--parse-byday-entry-error-garbage-nil ()
+  "Error: an unrecognizable entry returns nil."
+  (should (null (calendar-sync--parse-byday-entry "XX")))
+  (should (null (calendar-sync--parse-byday-entry "")))
+  (should (null (calendar-sync--parse-byday-entry nil))))
+
+(provide 'test-calendar-sync--parse-byday-entry)
+;;; test-calendar-sync--parse-byday-entry.el ends here