OrderService

package hello.core.order;

public interface OrderService {
    Order createOrder(Long memberId, String itemName, int itemPrice);
}
//interface

package hello.core.order;

public class Order {

    private  Long memberId;
    private String  itemName;
    private int itemPrice;
    private int discountPrice;

    public Order(Long memberId, String itemName, int itemPrice, int discountPrice) {
        this.memberId = memberId;
        this.itemName = itemName;
        this.itemPrice = itemPrice;
        this.discountPrice = discountPrice;
    }

    //할인 적용 후 결과 가격 계산
    public int calculatePrice(){
        return itemPrice-discountPrice;
    }

    public Long getMemberId() {
        return memberId;
    }

    public void setMemberId(Long memberId) {
        this.memberId = memberId;
    }

    public String getItemName() {
        return itemName;
    }

    public void setItemName(String itemName) {
        this.itemName = itemName;
    }

    public int getItemPrice() {
        return itemPrice;
    }

    public void setItemPrice(int itemPrice) {
        this.itemPrice = itemPrice;
    }

    public int getDiscountPrice() {
        return discountPrice;
    }

    public void setDiscountPrice(int discountPrice) {
        this.discountPrice = discountPrice;
    }

    //출력할 때 결과를 보기 쉽게 하기 위한 toString() 메소드 (Generate에서 생성 가능)
    @Override
    public String toString() {
        return "Order{" +
                "memberId=" + memberId +
                ", itemName='" + itemName + '\'' +
                ", itemPrice=" + itemPrice +
                ", discountPrice=" + discountPrice +
                '}';
    }
}
// OrderServiceImpl.java

package hello.core.discount;

import hello.core.member.Member;

public interface DiscountPolicy {

    //@return 할인 대상 금액
    int discount(Member member, int price);
}
// DiscountPolicy.java

package hello.core.discount;

import hello.core.member.Grade;
import hello.core.member.Member;

public class FIxDiscountPolicy implements DiscountPolicy{

    private int discountFixAmount = 1000;

    @Override
    public int discount(Member member, int price) {

        if(member.getGrade() == Grade.VIP){
            return discountFixAmount;
        }
        else {
            return 0;
        }
    }
}
//FixDiscountPolicy.java

package hello.core.order;

import hello.core.member.Grade;
import hello.core.member.Member;
import hello.core.member.MemberService;
import hello.core.member.MemberServiceImpl;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.Test;

public class OrderServiceTest {

    MemberService memberService = new MemberServiceImpl();
    OrderService orderService = new OrderServiceImpl();

    @Test
    void createOrder(){
        Long memberId = 1L;
        Member member = new Member(memberId, "memberA", Grade.VIP);
        memberService.join(member);

        Order order = orderService.createOrder(memberId, "itemA", 10000);

        Assertions.assertThat(order.getDiscountPrice()).isEqualTo(1000);

    }

}
// OrderServiceTest.java