A black box test of a class is a program that tests the correctness of the class's member functions without directly examining the private members of the class. You can imagine that the private members are inside an opaque black box where they cannot be seen, so all testing must occur only through activating the public member functions.

Write a black box test program for the bag class. Make sure that you test the boundary values, such as an empty bag, a bag with one item, and a full bag.