(b) Consider the following code: (18 marks class TimeDuration { // the duration can only be set during construction TimeDuration(int totalSeconds) {--} // getter methods representing the number of hours, minutes, // and seconds represented by totalSeconds, e.g. 1/ 3785 total seconds is equivalent to 1hr, 3min, and 5 sec int getHours() {-} int getMinutes() {-} int getSeconds() {-} // return a new duration object representing the // difference between this duration and other TimeDuration subtract(TimeDuration& other) {...} ) Outline a set of closed-box (specification based) unit tests for the getter methods and the subtract method in the class above. You may use pseudocode descriptions, but you must be specific about the test values used