test(calendar-sync): add 68 tests across 13 files for untested pure functions

Covers core parsing (parse-ics-datetime, parse-timestamp, format-timestamp,
split-events, parse-event), date utilities (add-months, add-days,
weekday-to-number, date-weekday, event-start-time), and timezone
(format-timezone-offset, convert-utc-to-local, localize-parsed-datetime).

1 files changed, 82 insertions, 0 deletions

diff --git a/tests/test-calendar-sync--parse-event.el b/tests/test-calendar-sync--parse-event.el
new file mode 100644
index 00000000..9c343db2
--- /dev/null
+++ b/tests/test-calendar-sync--parse-event.el
@@ -0,0 +1,82 @@
+;;; test-calendar-sync--parse-event.el --- Tests for VEVENT parser -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for calendar-sync--parse-event.
+;; Parses VEVENT string into plist with :uid :summary :start :end etc.
+;; Uses dynamic timestamps via testutil-calendar-sync helpers.
+
+;;; Code:
+
+(require 'ert)
+(require 'testutil-calendar-sync)
+(require 'calendar-sync)
+
+;;; Normal Cases
+
+(ert-deftest test-calendar-sync--parse-event-normal-basic-fields ()
+  "Basic event returns plist with summary, start, end."
+  (let* ((start (test-calendar-sync-time-days-from-now 5 14 0))
+         (end (test-calendar-sync-time-days-from-now 5 15 0))
+         (vevent (test-calendar-sync-make-vevent "Team Standup" start end)))
+    (let ((result (calendar-sync--parse-event vevent)))
+      (should result)
+      (should (equal "Team Standup" (plist-get result :summary)))
+      (should (plist-get result :start))
+      (should (plist-get result :end)))))
+
+(ert-deftest test-calendar-sync--parse-event-normal-optional-fields ()
+  "Event with description and location includes them."
+  (let* ((start (test-calendar-sync-time-days-from-now 5 14 0))
+         (end (test-calendar-sync-time-days-from-now 5 15 0))
+         (vevent (test-calendar-sync-make-vevent
+                  "Meeting" start end "Discuss roadmap" "Room 42")))
+    (let ((result (calendar-sync--parse-event vevent)))
+      (should (equal "Discuss roadmap" (plist-get result :description)))
+      (should (equal "Room 42" (plist-get result :location))))))
+
+(ert-deftest test-calendar-sync--parse-event-normal-all-day ()
+  "All-day event (date-only) is parsed correctly."
+  (let* ((start (test-calendar-sync-time-date-only 5))
+         (end (test-calendar-sync-time-date-only 6))
+         (vevent (test-calendar-sync-make-vevent "Holiday" start end)))
+    (let ((result (calendar-sync--parse-event vevent)))
+      (should result)
+      (should (= 3 (length (plist-get result :start)))))))
+
+;;; Boundary Cases
+
+(ert-deftest test-calendar-sync--parse-event-boundary-recurrence-id-skipped ()
+  "Events with RECURRENCE-ID are skipped (return nil)."
+  (let* ((start (test-calendar-sync-time-days-from-now 5 14 0))
+         (vevent (concat "BEGIN:VEVENT\n"
+                         "SUMMARY:Modified Instance\n"
+                         "DTSTART:" (test-calendar-sync-ics-datetime start) "\n"
+                         "RECURRENCE-ID:" (test-calendar-sync-ics-datetime start) "\n"
+                         "END:VEVENT")))
+    (should (null (calendar-sync--parse-event vevent)))))
+
+(ert-deftest test-calendar-sync--parse-event-boundary-no-end-time ()
+  "Event without DTEND still parses (end is nil)."
+  (let* ((start (test-calendar-sync-time-days-from-now 5 14 0))
+         (vevent (concat "BEGIN:VEVENT\n"
+                         "SUMMARY:Open-ended\n"
+                         "DTSTART:" (test-calendar-sync-ics-datetime start) "\n"
+                         "END:VEVENT")))
+    (let ((result (calendar-sync--parse-event vevent)))
+      (should result)
+      (should (null (plist-get result :end))))))
+
+;;; Error Cases
+
+(ert-deftest test-calendar-sync--parse-event-error-no-summary ()
+  "Event without SUMMARY returns nil."
+  (let ((vevent "BEGIN:VEVENT\nDTSTART:20260315T140000Z\nEND:VEVENT"))
+    (should (null (calendar-sync--parse-event vevent)))))
+
+(ert-deftest test-calendar-sync--parse-event-error-no-dtstart ()
+  "Event without DTSTART returns nil."
+  (let ((vevent "BEGIN:VEVENT\nSUMMARY:Orphan\nEND:VEVENT"))
+    (should (null (calendar-sync--parse-event vevent)))))
+
+(provide 'test-calendar-sync--parse-event)
+;;; test-calendar-sync--parse-event.el ends here