// As an owner, I want to add an item
 public void testAddCard() {
   Inventory inv = new Inventory();
   // GCard constructor: public GCard(String name, int value, int quantity, int quality (out of 5),
   //                                   String category, bool shared, String comment)
   GCard gcard =
       new GCard("Starbucks", 20, 1, 4, "Food & Drink", True, "Will get you half a coffee");
   // inv.addCard(gcard);
   if (inv.hasCard(gcard)) {
     throw new IllegalArgumentException();
   }
   inv.addCard(gcard);
   assertTrue(inv.hasCard(gcard));
 }
 public void testHasCard() {
   Inventory inv = new Inventory();
   Tweet gcard =
       new GCard("Starbucks", 20, 1, 4, "Food & Drink", True, "Will get you half a coffee");
   inv.addCard(gcard);
   assertTrue(inv.hasCard(gcard));
 }
 // As an owner, I want to remove an item
 // As an owner, I want to delete inventory items
 public void testDelete() {
   Inventory inv = new Inventory();
   GCard gcard =
       new GCard("Starbucks", 20, 1, 4, "Food & Drink", True, "Will get you half a coffee");
   inv.addCard(gcard);
   inv.removeCard(gcard);
   assertFalse(inv.hasCard(gcard));
 }