[Order API TDD] 상품 수정 기능 POJO 구현 및 Stub 클래스를 활용한 테스트

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

@@ -26,4 +26,13 @@ public Product(final String name, final int price, final DiscountPolicy discount
         this.price = price;
         this.discountPolicy = discountPolicy;
     }
+
+    public void update(final String name, final int price, final DiscountPolicy discountPolicy) {
+        Assert.hasText(name, "상품명은 필수입니다.");
+        Assert.isTrue(price > 0, "상품 가격은 0보다 커야 합니다.");
+        Assert.notNull(discountPolicy, "할인 정책은 필수입니다.");
+        this.name = name;
+        this.price = price;
+        this.discountPolicy = discountPolicy;
+    }
 }

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

@@ -35,4 +35,12 @@ public ResponseEntity<GetProductResponse> getProduct(@PathVariable final long pr
                 product.getDiscountPolicy());
         return ResponseEntity.ok(response);
     }
+
+    public void updateProduct(final Long productId, final UpdateProductRequest request) {
+        final Product product = productPort.getProduct(productId);
+
+        product.update(request.name(), request.price(), request.discountPolicy());
+
+        productPort.save(product);
+    }
 }

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

@@ -0,0 +1,14 @@
+package com.example.productorderservice.product;
+
+import org.springframework.util.Assert;
+
+record UpdateProductRequest(
+        String name,
+        int price,
+        DiscountPolicy discountPolicy) {
+    UpdateProductRequest {
+        Assert.hasText(name, "상품명은 필수입니다.");
+        Assert.isTrue(price > 0, "상품 가격은 0보다 커야 합니다.");
+        Assert.notNull(discountPolicy, "할인 정책은 필수입니다.");
+    }
+}

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

@@ -0,0 +1,47 @@
+package com.example.productorderservice.product;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class ProductServiceTest {
+
+    private ProductService productService;
+    private StubProductPort productPort = new StubProductPort();
+
+    @BeforeEach
+    void setUp() {
+        productService = new ProductService(productPort);
+    }
+
+    @Test
+    void updateProduct() {
+        final Long productId = 1L;
+        final String name = "상품 수정";
+        int price = 2000;
+        final DiscountPolicy discountPolicy = DiscountPolicy.NONE;
+        final UpdateProductRequest request = new UpdateProductRequest(name, price, discountPolicy);
+        final Product product = new Product("상품명", 1000, DiscountPolicy.NONE);
+        productPort.getProduct_will_return = product;
+
+        productService.updateProduct(productId, request);
+
+        Assertions.assertEquals("상품 수정", product.getName());
+        Assertions.assertEquals(2000, product.getPrice());
+    }
+
+    private class StubProductPort implements ProductPort {
+
+        public Product getProduct_will_return;
+
+        @Override
+        public void save(final Product product) {
+            throw new UnsupportedOperationException("StubProductPort#save not implemented yet !!");
+        }
+
+        @Override
+        public Product getProduct(final long productId) {
+            return getProduct_will_return;
+        }
+    }
+}

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

@@ -0,0 +1,17 @@
+package com.example.productorderservice.product;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+class ProductTest {
+
+    @Test
+    void update() {
+        final Product product = new Product("상품명", 1000, DiscountPolicy.NONE);
+
+        product.update("상품 수정", 2000, DiscountPolicy.NONE);
+
+        Assertions.assertEquals("상품 수정", product.getName());
+        Assertions.assertEquals(2000, product.getPrice());
+    }
+}