[Order API TDD] POJO 상품 주문 기능 구현하기

product-order-service/README.md

@@ -108,6 +108,31 @@ final UpdateProductRequest request = new UpdateProductRequest(name, price, disco
 
 > [POJO Test to SpringBoot Test]()
 
+### API 테스트로 전환하기
+
+> [API 테스트로 전환하기]()
+
+## 상품 주문 기능 구현하기
+
+**POJO**
+
+**스프링부트 테스트로 전환하기**
+
+**API 테스트로 전환하기**
+
+**JPA 적용**
+
+## 주문 결제 기능 구현하기
+
+**POJO**
+
+**스프링부트 테스트로 전환하기**
+
+
+**API 테스트로 전환하기**
+
+**JPA 적용**
+
 ---
 
 Point.
@@ -119,6 +144,39 @@ Point.
 - HttpStatus
   - 200 OK
   - 201 CREATE
+
+---
+
+Reference.
+
+**intellij introduce variable final**
+- Preference -> Editor -> Code Style -> Java -> Code Generation -> Final Modifier
+  - Make generated local variables final
+  - Make generated parameters final
+
+**Live Templates**
+- Preferences -> Editor -> Live Templates
+
+**Inspections**
+- Preferences -> Editor -> Inspections
+  - Local variable or parameter can be final
+
+**extract variable final**
+- option + command + v
+- option + shift + O
+  - Declare final
+  - Declare var
+
+**extract method final**
+- option + command + m
+- option + shift + O
+  - make static
+
+**code vision usages**
+- Preferences -> Editor -> Inlay Hints -> Java -> Code vision -> Show hints for
+  - Usages
+  - inheritors
+
 
 ---
 

product-order-service/src/main/java/com/example/productorderservice/product/DiscountPolicy.java

@@ -1,5 +1,5 @@
 package com.example.productorderservice.product;
 
-enum DiscountPolicy {
+public enum DiscountPolicy {
     NONE
 }

product-order-service/src/main/java/com/example/productorderservice/product/Product.java

@@ -10,7 +10,7 @@
 @Table(name = "products")
 @Getter
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
-class Product {
+public class Product {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;

product-order-service/src/main/java/com/example/productorderservice/product/ProductRepository.java

@@ -2,5 +2,5 @@
 
 import org.springframework.data.jpa.repository.JpaRepository;
 
-interface ProductRepository extends JpaRepository<Product, Long> {
+public interface ProductRepository extends JpaRepository<Product, Long> {
 }

product-order-service/src/test/java/com/example/productorderservice/order/OrderServiceTest.java

@@ -0,0 +1,125 @@
+package com.example.productorderservice.order;
+
+import com.example.productorderservice.product.DiscountPolicy;
+import com.example.productorderservice.product.Product;
+import com.example.productorderservice.product.ProductRepository;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.util.Assert;
+
+import java.util.HashMap;
+import java.util.Map;
+
+class OrderServiceTest {
+
+    private OrderService orderService;
+    private OrderPort orderPort;
+    private OrderRepository orderRepository;
+
+    @BeforeEach
+    void setUp() {
+        orderRepository = new OrderRepository();
+        orderPort = new OrderPort() {
+            @Override
+            public Product getProductById(final long productId) {
+                return new Product("상품명", 1000, DiscountPolicy.NONE);
+            }
+
+            @Override
+            public void save(final Order order) {
+                orderRepository.save(order);
+            }
+        };
+        orderService = new OrderService(orderPort);
+    }
+
+    @Test
+    void 상품주문() {
+        final long productId = 1L;
+        final int quantity = 2;
+        final CreateOrderRequest request = new CreateOrderRequest(productId, quantity);
+
+        orderService.createOrder(request);
+    }
+
+    private record CreateOrderRequest(long productId, int quantity) {
+        private CreateOrderRequest {
+            Assert.notNull(productId, "상품 ID는 필수입니다.");
+            Assert.isTrue(quantity > 0, "수량은 0보다 커야 합니다.");
+        }
+    }
+
+    private class OrderService {
+        private final OrderPort orderPort;
+
+        private OrderService(final OrderPort orderPort) {
+            this.orderPort = orderPort;
+        }
+
+        public void createOrder(final CreateOrderRequest request) {
+            final Product product = orderPort.getProductById(request.productId());
+
+            final Order order = new Order(product, request.quantity());
+
+            orderPort.save(order);
+        }
+    }
+
+    private class OrderAdapter implements OrderPort{
+
+        private final ProductRepository productRepository;
+        private final OrderRepository orderRepository;
+
+        private OrderAdapter(final ProductRepository productRepository, final OrderRepository orderRepository) {
+            this.productRepository = productRepository;
+            this.orderRepository = orderRepository;
+        }
+
+        @Override
+        public Product getProductById(final long productId) {
+            return productRepository.findById(productId)
+                    .orElseThrow(() -> new IllegalArgumentException("상품이 존재하지 않습니다."));
+        }
+
+        @Override
+        public void save(final Order order) {
+            orderRepository.save(order);
+        }
+    }
+
+    private class Order {
+        private Long id;
+        private final Product product;
+        private final int quantity;
+
+        public Order(final Product product, final int quantity) {
+            Assert.notNull(product, "상품은 필수입니다.");
+            Assert.isTrue(quantity > 0, "수량은 0보다 커야 합니다.");
+            this.product = product;
+            this.quantity = quantity;
+        }
+
+        public void assignId(final Long id) {
+            this.id = id;
+        }
+
+        public Long getId() {
+            return id;
+        }
+    }
+
+    private class OrderRepository {
+        private Map<Long, Order> persistence = new HashMap<>();
+        private Long sequance = 0L;
+
+        public void save(final Order order) {
+            order.assignId(++sequance);
+            persistence.put(order.getId(), order);
+        }
+    }
+
+    private interface OrderPort {
+        Product getProductById(final long productId);
+        void save(final Order order);
+    }
+}