Consider the following interface for an ADT for representing intervals (periods of time as opposed to instantaneous moments of time).

typedef long Duration; // measured in seconds class DateTime { public: DateTime (int year, int month, int day, int hour, int minute, int second); 

 ... // How many seconds between two times? Duration operator- (const DateTime& right) const; }; class Interval { public: // // An interval is a period of time beginning with a starting time // and running up to, but not including, its stop time. // Interval (); Interval (DateTime start, DateTime stop); Interval (DateTime start, Duration length); DateTime getStart() const; void setStart (DateTime); DateTime getStop() const; void setStop (DateTime); Duration getDuration(); bool contains (DateTime d); bool overlaps (Interval intrvl); bool operator== (const Interval& other) const; 

private: DateTime theStart, theStop; }; 

Using the JUnit style, write a self-checking test for the 3rd Interval constuctor.