Spring Boot MockMvc 测试：如何传递 JSON 请求体对象

public class CartDto {
    private String itemId;
    private int quantity;
    // Getters and Setters
    public CartDto() {} // Default constructor is often required by Jackson
    public CartDto(String itemId, int quantity) {
        this.itemId = itemId;
        this.quantity = quantity;
    }

    public String getItemId() {
        return itemId;
    }

    public void setItemId(String itemId) {
        this.itemId = itemId;
    }

    public int getQuantity() {
        return quantity;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }
}

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.JsonProcessingException;

// ... 在你的测试类中 ...

ObjectMapper objectMapper = new ObjectMapper();
CartDto cartDto = new CartDto("item001", 2);

String jsonContent;
try {
    jsonContent = objectMapper.writeValueAsString(cartDto);
} catch (JsonProcessingException e) {
    // 处理序列化异常，例如记录日志或抛出运行时异常
    throw new RuntimeException("Failed to serialize CartDto to JSON", e);
}

System.out.println("Generated JSON: " + jsonContent);
// 预期输出示例: Generated JSON: {"itemId":"item001","quantity":2}

import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.http.MediaType;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

// ... 在你的测试类中 ...

// 假设 mockMvc 已经被 @Autowired 或手动初始化
// @Autowired
// private MockMvc mockMvc;

// ... 接续上面的 jsonContent 生成代码 ...

mockMvc.perform(MockMvcRequestBuilders.post("/user/addItemIntoCart")
        .contentType(MediaType.APPLICATION_JSON) // 声明请求体是JSON格式
        .content(jsonContent)) // 将JSON字符串作为请求体内容
        .andExpect(status().isOk()) // 期望HTTP状态码为200 OK
        .andReturn(); // 获取MvcResult

import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.when;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;

// 模拟的 CartDto 类
class CartDto {
    private String itemId;
    private int quantity;

    public CartDto() {}
    public CartDto(String itemId, int quantity) {
        this.itemId = itemId;
        this.quantity = quantity;
    }

    public String getItemId() { return itemId; }
    public void setItemId(String itemId) { this.itemId = itemId; }
    public int getQuantity() { return quantity; }
    public void setQuantity(int quantity) { this.quantity = quantity; }
}

// 模拟的 CartService 接口
interface CartService {
    ResponseEntity<String> addItemIntoCart(CartDto cartDto);
}

// 模拟的 UserController
@RestController
@RequestMapping("/user")
class UserController {
    private final CartService cartService;

    public UserController(CartService cartService) {
        this.cartService = cartService;
    }

    @PostMapping(value = "/addItemIntoCart", consumes = {"application/json"})
    public ResponseEntity<String> addItemToCart(@RequestBody CartDto cartDto) {
        return cartService.addItemIntoCart(cartDto);
    }
}

@WebMvcTest(UserController.class) // 针对 UserController 进行 Web 层测试
public class UserControllerTest {

    @Autowired
    private MockMvc mockMvc;

    @MockBean // 模拟 CartService，避免真实的服务层调用
    private CartService cartService;

    private ObjectMapper objectMapper;

    @BeforeEach
    void setUp() {
        objectMapper = new ObjectMapper(); // 初始化 ObjectMapper
    }

    @Test
    void testAddItemIntoCart() throws Exception {
        // 1. 准备待发送的 CartDto 对象
        CartDto cartDto = new CartDto("productXYZ", 3);

        // 2. 将 CartDto 对象序列化为 JSON 字符串
        String jsonContent = objectMapper.writeValueAsString(cartDto);

        // 3. 模拟 CartService 的行为（可选，但通常需要）
        // 当 cartService.addItemIntoCart 被调用时，返回一个成功的 ResponseEntity
        when(cartService.addItemIntoCart(any(CartDto.class)))
                .thenReturn(ResponseEntity.ok("Item added successfully"));

        // 4. 构建 MockMvc 请求并发送 JSON 内容
        mockMvc.perform(post("/user/addItemIntoCart")
                .contentType(MediaType.APPLICATION_JSON) // 设置 Content-Type
                .content(jsonContent)) // 设置请求体内容
                .andExpect(status().isOk()) // 验证 HTTP 状态码是否为 200 OK
                .andExpect(content().string("Item added successfully")); // 验证响应体内容
    }
}