fix: make mergeDateAndTime work across DST changes

src/dates/dates.spec.ts

@@ -42,9 +42,15 @@ describe('Date Helpers', () => {
 			];
 
 			for (const el of data) {
-				expect(mergeDateAndTime(el.date, new Time(el.time)).format()).toBe(el.expected.format());
+				expect(mergeDateAndTime(el.date, new Time(el.time))).toBeSameMoment(el.expected);
 			}
 		});
+
+		it('should work across DST changes', () => {
+			const date = moment('2020-04-05T00:00:00');
+
+			expect(mergeDateAndTime(date, new Time('12:34'))).toBeSameMoment(moment('2020-04-05T12:34:00'));
+		});
 	});
 
 	describe('minsToMs(number)', () => {

src/dates/index.ts

@@ -10,10 +10,16 @@ declare const moment: typeof import('moment-timezone');
  * @param date The date to merge the time into
  * @param time The time to merge into the date
  */
-export const mergeDateAndTime = (date: Moment | string, time: Time) =>
-	moment(date)
+export const mergeDateAndTime = (date: Moment | string, time: Time) => {
+	const [hours, minutes] = time
+		.toString()
+		.split(':')
+		.map(Number);
+
+	return moment(date)
 		.startOf('day')
-		.add(time.valueOf(), 'minutes');
+		.set({ hours, minutes });
+};
 
 /**
  * Convert minutes to milliseconds.

src/time/index.ts

@@ -59,8 +59,8 @@ export class Time {
 	/**
 	 * Add a number of minutes and return a new Time instance with the new value.
 	 *
-	 * This is circular, e. g. when removing 5 minutes from 00:00, the resulting
-	 * time will be 23:55, and when adding 5 mins to 23:55, it will be 00:00.
+	 * This is circular, e. g. when removing 10 minutes from 00:05, the resulting
+	 * time will be 23:55, and when adding 10 mins to 23:55, it will be 00:05.
 	 */
 	add(mins: number) {
 		let newValue = (this.value + mins) % 1440;