# 주문과 할인 실행과 테스트

주문 도메인 전체

![주문 도메인 전체 다이어그램](blob:https://app.gitbook.com/e233c399-2ba7-403e-a6a3-1806b312807b)

1. **Order 클래스 생성**

2. **OrderService 인터페이스 생성**

3. **DiscountPolicy 인터페이스 생성**

4. **OrderService 구현체 생성 : OrderServiceImpl**

5. **DiscountPolicy 구현체 생성 : FixDiscountPolicy**

6. **테스트코드 작성**

7. Order 클래스 생성

```java
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;
    }
    //비즈니스 로직 - 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;
    }

    @Override
    public String toString() {
        return "Order{" +
                "memberId=" + memberId +
                ", itemName='" + itemName + '\'' +
                ", itemPrice=" + itemPrice +
                ", discountPrice=" + discountPrice +
                '}';
    }
}
```

2\. OrderService 인터페이스 생성

```java
package hello.core.order;

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

3\. DiscountPolicy 인터페이스 생성

```java
package hello.core.discount;

import hello.core.member.Member;

public interface DiscountPolicy {
    /*
    @return 할인 대상 금액
     */
    int discount(Member member, int price);
}

```

4\. OrderService 구현체 생성 : OrderServiceImpl

```java
package hello.core.order;

import hello.core.discount.DiscountPolicy;
import hello.core.discount.FixDiscountPolicy;
import hello.core.member.Member;
import hello.core.member.MemberRepository;
import hello.core.member.MemoryMemberRepository;

public class OrderServiceImpl implements OrderService{

    private final MemberRepository memberRepository = new MemoryMemberRepository();
    private final DiscountPolicy discountPolicy = new FixDiscountPolicy();//인터페이스에 의존하면섣도 구현체를 할당받고 사용하고 있다!!
    @Override
    public Order createOrder(Long memberId, String itemName, int itemPrice) {
        //회원을 먼저 찾고
        Member member = memberRepository.findById(memberId);
        //단일책임원칙을 잘 지키며 할인에 대한 역할은 discountPolicy에 넘긴다!
        int discountPrice = discountPolicy.discount(member,itemPrice);
        return new Order(memberId,itemName,itemPrice,discountPrice);//주문결과 반환.
    }
}
```

5\. DiscountPolicy 구현체 생성 : FixDiscountPolicy

```java
package hello.core.discount;

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

public class FixDiscountPolicy implements DiscountPolicy{
    private int discountFixAmount = 1000;//1000원 할인
    @Override
    public int discount(Member member, int price) {
        //enum타입은 == 쓰는 게 맞다.
        if(member.getGrade() == Grade.VIP){
            return discountFixAmount;
        } else{
            return 0;
        }
    }
}
```

6\. 테스트코드 작성

```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);
    }
}
```

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