public void TestBookingAddActivity()
        {
            //instanciate mock objects
            Client    mockClient   = Substitute.For <Client>("CliID", "CoName", "CoAddress");
            Date      mockDate     = Substitute.For <Date>(12, 9, 2019);
            Time      mockTime     = Substitute.For <Time>(12, 54);
            IVenue    mockVenue    = Substitute.For <IVenue>();
            IActivity mockActivity = Substitute.For <IActivity>();
            string    ID           = "123";

            Booking booking = new Booking(ID, BookingType.SIMPLE,
                                          mockClient, mockDate, mockTime, mockVenue);

            booking.AddActivity(mockActivity);
            Assert.AreEqual(mockActivity, booking.activity);
        }
        public void TestBookingUpdateGetCost()
        {
            //instanciate mock objects
            Client    mockClient   = Substitute.For <Client>("CliID", "CoName", "CoAddress");
            IVenue    mockVenue    = Substitute.For <IVenue>();
            Date      mockDate     = Substitute.For <Date>(12, 9, 2019);
            Time      mockTime     = Substitute.For <Time>(12, 54);
            IActivity mockActivity = Substitute.For <IActivity>();
            string    ID           = "123";

            Booking booking = new Booking(ID, BookingType.SIMPLE,
                                          mockClient, mockDate, mockTime, mockVenue);

            booking.AddActivity(mockActivity);

            mockVenue.cost.Returns(15);
            mockActivity.cost.Returns(12);

            Assert.AreEqual <decimal>(27, booking.GetCost());
        }