get cart - api contract (step5)

src/main/java/group/rohlik/application/CartFetcher.java

@@ -0,0 +1,53 @@
+package group.rohlik.application;
+
+import group.rohlik.entity.Cart;
+import group.rohlik.entity.CartRepository;
+import group.rohlik.entity.Discount;
+import lombok.AllArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.Comparator;
+import java.util.List;
+
+@AllArgsConstructor
+@Service
+@Transactional(readOnly = true)
+public class CartFetcher {
+
+    private final CartRepository cartRepository;
+
+    public CartDetail fetch(long cartId) {
+        Cart cart = cartRepository.findById(cartId).orElseThrow();
+
+        return new CartDetail(
+                cart.getId(),
+                cart.totalPrice(),
+                cart
+                        .getLines()
+                        .stream()
+                        .map(line -> new Line(line.getProduct().getSku(), line.getProduct().getName(), line.getQuantity()))
+                        .sorted(Comparator.comparing(line -> line.sku))
+                        .toList(),
+                cart
+                        .getDiscounts()
+                        .stream()
+                        .map(Discount::getName)
+                        .sorted()
+                        .toList()
+        );
+    }
+
+    private record CartDetail(
+            long id,
+            double total,
+            List<Line> lines,
+            List<String> discounts
+    ) { }
+
+    private record Line(
+            String sku,
+            String name,
+            int quantity
+    ) { }
+}

src/main/java/group/rohlik/controller/CartController.java

@@ -1,11 +1,13 @@
 package group.rohlik.controller;
 
 import com.fasterxml.jackson.databind.JsonNode;
+import group.rohlik.application.CartFetcher;
 import group.rohlik.application.CartDiscountAdder;
 import group.rohlik.application.CartLineAdder;
 import lombok.AllArgsConstructor;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
@@ -17,6 +19,7 @@ public class CartController {
 
     private final CartLineAdder cartLineAdder;
     private final CartDiscountAdder cartDiscountAdder;
+    private final CartFetcher cartFetcher;
 
     @PostMapping(path = "/carts/{id}/lines", consumes = "application/json", produces = "application/json")
     public ResponseEntity addLine(@PathVariable long id, @RequestBody JsonNode payload) {
@@ -36,4 +39,11 @@ public ResponseEntity addDiscount(@PathVariable long id, @RequestBody JsonNode p
 
         return new ResponseEntity<>(HttpStatus.OK);
     }
+
+    @GetMapping(path = "/carts/{id}", consumes = "application/json", produces = "application/json")
+    public ResponseEntity<Object> recoverCartDetail(@PathVariable long id) {
+        var cartDetail = cartFetcher.fetch(id);
+
+        return new ResponseEntity<>(cartDetail, HttpStatus.OK);
+    }
 }

src/test/java/group/rohlik/acceptance/steps/HttpSteps.java

@@ -0,0 +1,45 @@
+package group.rohlik.acceptance.steps;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.cucumber.java.Before;
+import io.cucumber.java.en.Then;
+import io.cucumber.java.en.When;
+import lombok.RequiredArgsConstructor;
+import org.junit.jupiter.api.Assertions;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+
+@RequiredArgsConstructor
+public class HttpSteps {
+
+    private final TestRestTemplate template;
+    private ResponseEntity<String> response;
+
+    @Before
+    public void setUp() {
+        response = null;
+    }
+
+    @When("I send a {string} request to {string}")
+    public void sendARequestWithBodyToWith(String method, String path) {
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(MediaType.APPLICATION_JSON);
+
+        HttpEntity<String> entity = new HttpEntity<>(null, headers);
+        response = template.exchange(path, HttpMethod.resolve(method.toUpperCase()), entity, String.class);
+    }
+
+    @Then("the response status should be {int} with body:")
+    public void theResponseStatusAndBodyShouldBe(int status, String body) throws JsonProcessingException {
+        ObjectMapper mapper = new ObjectMapper();
+
+        Assertions.assertEquals(response.getStatusCode(), HttpStatus.resolve(status));
+        Assertions.assertEquals(mapper.readTree(body), mapper.readTree(response.getBody()));
+    }
+}

src/test/resources/features/get_cart_detail.feature

@@ -0,0 +1,37 @@
+Feature: Get cart detail
+
+  Background:
+    Given the following products exist:
+      | sku | name     | price |
+      | 001 | potatoes | 2.5   |
+      | 002 | water    | 0.95  |
+    And there is a cart discount "free shipping" for 10 % with code "FREE-SHIPPING"
+    And I have a cart
+    And I add 2 units of product "001" to my cart
+    And I add 1 units of product "002" to my cart
+    And I apply "FREE-SHIPPING" discount to my cart
+
+  Scenario: Get cart details
+    When I send a "GET" request to "/carts/1"
+    Then the response status should be 200 with body:
+    """
+    {
+      "id": 1,
+      "total": 5.36,
+      "lines": [
+        {
+          "sku": "001",
+          "name": "potatoes",
+          "quantity": 2
+        },
+        {
+          "sku": "002",
+          "name": "water",
+          "quantity": 1
+        }
+      ],
+      "discounts": [
+        "free shipping"
+      ]
+    }
+    """