/**
 * A test client
 */
public class Test {
 public static void main(String[] args) {
 ShopContext myContext = new ShopContext();
 ShopState myShop = Shop.getInstance();
 ShopState myGenBill = GenerateBill.getInstance();
 ShopState myPay = Pay.getInstance();
 
 myContext.changeState(myShop);
 myContext.shop();

 myContext.changeState(myGenBill);
 myContext.generateBill();
 
 myContext.changeState(myPay);
 myContext.pay();

 myShop.changeState(myContext, myPay);
 myContext.pay();
 }
}