feat: add date functions Before, After and Compare

timex/date.go

@@ -26,6 +26,30 @@ func ParseDate(s string) (Date, error) {
 	return NewDateFromTime(t), nil
 }
 
+func (d Date) Before(d2 Date) bool {
+	if d.Year != d2.Year {
+		return d.Year < d2.Year
+	}
+	if d.Month != d2.Month {
+		return d.Month < d2.Month
+	}
+	return d.Day < d2.Day
+}
+
+func (d Date) After(d2 Date) bool {
+	return d2.Before(d)
+}
+
+func (d Date) Compare(d2 Date) int {
+	if d.Before(d2) {
+		return -1
+	}
+	if d.After(d2) {
+		return +1
+	}
+	return 0
+}
+
 func (d Date) String() string {
 	return fmt.Sprintf("%04d-%02d-%02d", d.Year, d.Month, d.Day)
 }

timex/date_test.go

@@ -29,6 +29,54 @@ func TestParseDate(t *testing.T) {
 		}
 	}
 }
+
+func TestDateBefore(t *testing.T) {
+	tests := []struct {
+		d1, d2 Date
+		want   bool
+	}{
+		{Date{1962, 12, 31}, Date{1963, 1, 1}, true},
+		{Date{1962, 1, 1}, Date{1962, 2, 1}, true},
+		{Date{1962, 1, 1}, Date{1962, 1, 1}, false},
+		{Date{1962, 12, 30}, Date{1962, 12, 31}, true},
+	}
+
+	for _, tt := range tests {
+		assert.Equal(t, tt.want, tt.d1.Before(tt.d2))
+	}
+}
+
+func TestDateAfter(t *testing.T) {
+	tests := []struct {
+		d1, d2 Date
+		want   bool
+	}{
+		{Date{1962, 12, 31}, Date{1963, 1, 1}, false},
+		{Date{1962, 1, 1}, Date{1962, 2, 1}, false},
+		{Date{1962, 1, 1}, Date{1962, 1, 1}, false},
+		{Date{1962, 12, 30}, Date{1962, 12, 31}, false},
+	}
+
+	for _, tt := range tests {
+		assert.Equal(t, tt.want, tt.d1.After(tt.d2))
+	}
+}
+
+func TestDateCompare(t *testing.T) {
+	tests := []struct {
+		d1, d2 Date
+		want   int
+	}{
+		{Date{1962, 12, 31}, Date{1963, 1, 1}, -1},
+		{Date{1962, 1, 1}, Date{1962, 1, 1}, 0},
+		{Date{1962, 12, 31}, Date{1962, 12, 30}, +1},
+	}
+
+	for _, tt := range tests {
+		assert.Equal(t, tt.want, tt.d1.Compare(tt.d2))
+	}
+}
+
 func TestMarshalJSON(t *testing.T) {
 	got, err := json.Marshal(Date{2023, 5, 4})
 	assert.Nil(t, err)