fix: daylight savings

rrule.go

@@ -666,12 +666,20 @@ func (iterator *rIterator) generate() {
 					continue
 				}
 				i := day.Int
-				dateYear, dateMonth, dateDay := iterator.ii.firstyday.AddDate(0, 0, i).Date()
+				date := iterator.ii.firstyday.AddDate(0, 0, i)
+				dateYear, dateMonth, dateDay := date.Date()
 				for _, timeTemp := range iterator.timeset {
 					tempHour, tempMinute, tempSecond := timeTemp.Clock()
-					res := time.Date(dateYear, dateMonth, dateDay,
-						tempHour, tempMinute, tempSecond,
-						timeTemp.Nanosecond(), timeTemp.Location())
+
+					var res time.Time
+					if r.freq < HOURLY {
+						res = time.Date(dateYear, dateMonth, dateDay,
+							tempHour, tempMinute, tempSecond,
+							timeTemp.Nanosecond(), timeTemp.Location())
+					} else {
+						res = date.Add(time.Duration(tempHour)*time.Hour + time.Duration(tempMinute)*time.Minute + time.Duration(tempSecond)*time.Second)
+					}
+
 					if !r.until.IsZero() && res.After(r.until) {
 						r.len = iterator.total
 						iterator.finished = true

rrule_test.go

@@ -1,5 +1,6 @@
 // 2017-2022, Teambition. All rights reserved.
 
+
 package rrule
 
 import (
@@ -3926,6 +3927,90 @@ func TestRuleChangeDTStartTimezoneRespected(t *testing.T) {
 	}
 }
 
+func TestDST_HourlyDSTStart(t *testing.T) {
+	sydLoc, _ := time.LoadLocation("Australia/Sydney")
+	r, _ := NewRRule(ROption{Freq: HOURLY, Interval: 1, Count: 3,
+		Dtstart: time.Date(2022, 10, 2, 1, 0, 0, 0, sydLoc),
+	})
+	got := r.All()
+	want := []string{
+		"2022-10-02 01:00:00 +1000 AEST",
+		"2022-10-02 03:00:00 +1100 AEDT",
+		"2022-10-02 04:00:00 +1100 AEDT",
+	}
+	for i, g := range got {
+		if g.String() != want[i] {
+			t.Errorf("got: %v, want: %v", g, want[i])
+		}
+	}
+	var utcTimes []time.Time
+	for _, dt := range got {
+		utcTimes = append(utcTimes, dt.UTC())
+	}
+	want = []string{
+		"2022-10-01 15:00:00 +0000 UTC",
+		"2022-10-01 16:00:00 +0000 UTC",
+		"2022-10-01 17:00:00 +0000 UTC",
+	}
+
+	for i, g := range utcTimes {
+		if g.String() != want[i] {
+			t.Errorf("got: %v, want: %v", g, want[i])
+		}
+	}
+}
+
+func TestDST_HourlyDSTEnd(t *testing.T) {
+	sydLoc, _ := time.LoadLocation("Australia/Sydney")
+	r, _ := NewRRule(ROption{Freq: HOURLY, Interval: 1, Count: 3,
+		Dtstart: time.Date(2023, 4, 2, 1, 0, 0, 0, sydLoc),
+	})
+	got := r.All()
+	want := []string{
+		"2023-04-02 01:00:00 +1100 AEDT",
+		"2023-04-02 02:00:00 +1100 AEDT",
+		"2023-04-02 02:00:00 +1000 AEST",
+	}
+	for i, g := range got {
+		if g.String() != want[i] {
+			t.Errorf("got: %v, want: %v", g, want[i])
+		}
+	}
+
+	var utcTimes []time.Time
+	for _, dt := range got {
+		utcTimes = append(utcTimes, dt.UTC())
+	}
+	want = []string{
+		"2023-04-01 14:00:00 +0000 UTC",
+		"2023-04-01 15:00:00 +0000 UTC",
+		"2023-04-01 16:00:00 +0000 UTC",
+	}
+	for i, g := range utcTimes {
+		if g.String() != want[i] {
+			t.Errorf("got: %v, want: %v", g, want[i])
+		}
+	}
+}
+
+
+func TestDailyDST(t *testing.T) {
+	sydney, _ := time.LoadLocation("Australia/Sydney")
+	r, _ := NewRRule(ROption{
+		Freq:    DAILY,
+		Count:   3,
+		Dtstart: time.Date(2023, 4, 1, 9, 0, 0, 0, sydney),
+	})
+	want := []time.Time{
+		time.Date(2023, 4, 1, 9, 0, 0, 0, sydney),
+		time.Date(2023, 4, 2, 9, 0, 0, 0, sydney),
+		time.Date(2023, 4, 3, 9, 0, 0, 0, sydney),
+	}
+	value := r.All()
+	if !timesEqual(value, want) {
+		t.Errorf("get %v, want %v", value, want)
+	}
+}
 func BenchmarkIterator(b *testing.B) {
 	type testCase struct {
 		Name   string