Bugfix/parse date with timezone param

lib/ical/deserialize.ex

@@ -442,13 +442,6 @@ defmodule ICal.Deserialize do
   @spec to_date(String.t() | nil, map, ICal.t()) :: Date.t() | DateTime.t() | nil
   def to_date(nil, _params, _calendar), do: nil
 
-  def to_date(date_string, %{"TZID" => timezone}, %ICal{default_timezone: default_timezone}) do
-    # Microsoft Outlook calendar .ICS files report times in Greenwich Standard Time (UTC +0)
-    # so just convert this to UTC
-    timezone = to_timezone(timezone, default_timezone)
-    to_date_in_timezone(date_string, timezone)
-  end
-
   def to_date(date_string, %{"VALUE" => "DATE"}, _calendar) do
     # of the form {YYYY}{MM}{DD}
     with <<y::binary-size(4), m::binary-size(2), d::binary-size(2)>> <- date_string,
@@ -462,6 +455,14 @@ defmodule ICal.Deserialize do
     end
   end
 
+  def to_date(date_string, %{"TZID" => timezone}, %ICal{default_timezone: default_timezone}) do
+    # Microsoft Outlook calendar .ICS files report times in Greenwich Standard Time (UTC +0)
+    # so just convert this to UTC
+    timezone = to_timezone(timezone, default_timezone)
+
+    to_date_in_timezone(date_string, timezone)
+  end
+
   def to_date(date_string, _params, %ICal{default_timezone: default_timezone}) do
     to_date_in_timezone(date_string, default_timezone)
   end

test/data/date_only_event.ics

@@ -0,0 +1,36 @@
+BEGIN:VCALENDAR
+METHOD:PUBLISH
+PRODID:ExampleProd
+VERSION:2.0
+X-WR-CALNAME:ExampleName
+X-WR-TIMEZONE:America/Edmonton
+BEGIN:VTIMEZONE
+TZID:America/Edmonton
+X-LIC-LOCATION:America/Edmonton
+BEGIN:STANDARD
+DTSTART:20241103T020000
+RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=11
+TZNAME:MST
+TZOFFSETFROM:-0600
+TZOFFSETTO:-0700
+END:STANDARD
+BEGIN:DAYLIGHT
+DTSTART:20250309T020000
+RRULE:FREQ=YEARLY;BYDAY=2SU;BYMONTH=3
+TZNAME:MDT
+TZOFFSETFROM:-0700
+TZOFFSETTO:-0600
+END:DAYLIGHT
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED;TZID=America/Edmonton:20260406T000000
+DTEND;TZID=America/Edmonton;VALUE=DATE:20260530
+DTSTAMP;TZID=America/Edmonton:20260406T000000
+DTSTART;TZID=America/Edmonton;VALUE=DATE:20260529
+SEQUENCE:2026052815
+SUMMARY:ExampleSummary
+UID:ExampleID
+X-FUNAMBOL-ALLDAY:1
+X-MICROSOFT-CDO-BUSYSTATUS:BUSY
+END:VEVENT
+END:VCALENDAR

test/ical/deserialize_test.exs

@@ -234,6 +234,20 @@ defmodule ICal.DeserializeTest do
       assert ICal.from_file("/does/not/exist.ics") == {:error, :enoent}
     end
 
+    test "Deserializing DATE fields with TZID params works correctly " do
+      # According to https://datatracker.ietf.org/doc/html/rfc5545#section-3.2.19
+      # this is not a RFC-conformant calendar, but ICal should still be able to parse it.
+      ics = Helper.test_data("date_only_event")
+      calendar = ICal.from_ics(ics)
+
+      assert Enum.count(calendar.events) == 1
+
+      [event] = calendar.events
+
+      assert event.dtstart == ~D[2026-05-29]
+      assert event.dtend == ~D[2026-05-30]
+    end
+
     test "Bad separators do not disturb parsing" do
       ics = Helper.test_data("broken_uid")
       %ICal{events: [event]} = ICal.from_ics(ics)

test/ical_test.exs

@@ -197,7 +197,7 @@ defmodule ICalTest do
     |> assert_fully_contains(expected)
   end
 
-  test "ICalender.to_ics/1 with exdates" do
+  test "ICal.to_ics/1 with exdates" do
     events = [
       %ICal.Event{
         exdates: [
@@ -216,7 +216,7 @@ defmodule ICalTest do
     assert ics =~ "EXDATE;TZID=America/Toronto:20200917T143000"
   end
 
-  test "ICalender.to_ics/1 with duration" do
+  test "ICal.to_ics/1 with duration" do
     events = [
       %ICal.Event{
         duration: %ICal.Duration{
@@ -236,7 +236,7 @@ defmodule ICalTest do
     assert ics =~ "DURATION:P15DT5H20S"
   end
 
-  test "ICalender.to_ics/1 with RECURRENCE-ID in UTC" do
+  test "ICal.to_ics/1 with RECURRENCE-ID in UTC" do
     events = [
       %ICal.Event{
         recurrence_id: ~U[2020-09-17 14:30:00Z],
@@ -252,7 +252,7 @@ defmodule ICalTest do
     assert ics =~ "RECURRENCE-ID:20200917T143000Z"
   end
 
-  test "ICalender.to_ics/1 with RECURRENCE-ID with timezone" do
+  test "ICal.to_ics/1 with RECURRENCE-ID with timezone" do
     recurrence_id = DateTime.shift_zone!(~U[2020-09-17 18:30:00Z], "America/Toronto")
 
     events = [
@@ -270,7 +270,7 @@ defmodule ICalTest do
     assert ics =~ "RECURRENCE-ID;TZID=America/Toronto:20200917T143000"
   end
 
-  test "ICalender.to_ics/1 -> ICal.from_ics/1 and back again" do
+  test "ICal.to_ics/1 -> ICal.from_ics/1 and back again" do
     events = [
       %ICal.Event{
         summary: "Film with Amy and Adam",
@@ -292,7 +292,7 @@ defmodule ICalTest do
     assert events |> List.first() == new_event
   end
 
-  test "ICalender.to_ics/1 -> ICal.from_ics/1 and back again, with newlines" do
+  test "ICal.to_ics/1 -> ICal.from_ics/1 and back again, with newlines" do
     events = [
       %ICal.Event{
         summary: "Film with Amy and Adam",
@@ -318,7 +318,7 @@ defmodule ICalTest do
     Regex.scan(~r/#{check_for}/, ics) |> Enum.count()
   end
 
-  test "ICalender.to_ics/1 supports bare components and lists of components" do
+  test "ICal.to_ics/1 supports bare components and lists of components" do
     assert %ICal{events: [%ICal.Event{}]}
            |> ICal.to_ics()
            |> to_string()