Add a test to construct clock with negative 120 minutes (#996)

* Add a test to construct clock with negative 120 minutes

* Cover hour wrapping as well

Author: shaaraddalvi

exercises/clock/tests/clock.rs

@@ -111,6 +111,12 @@ fn test_negative_sixty_minutes_is_prev_hour() {
     assert_eq!(Clock::new(2, -60).to_string(), "01:00");
 }
 
+#[test]
+#[ignore]
+fn test_negative_one_twenty_minutes_is_two_prev_hours() {
+    assert_eq!(Clock::new(1, -120).to_string(), "23:00");
+}
+
 #[test]
 #[ignore]
 fn test_negative_hour_and_minutes_both_roll_over() {