@WebMvcTest

Testing Spring MVC controllers with focused slice tests.

Basic Structure

@WebMvcTest(OrderController.class)
class OrderControllerTest {
  
  @Autowired
  private MockMvcTester mvc;
  
  @MockitoBean
  private OrderService orderService;
  
  @MockitoBean
  private UserService userService;
}

What Gets Loaded

• The specified controller(s)
• Spring MVC infrastructure (HandlerMapping, HandlerAdapter)
• Jackson ObjectMapper (for JSON)
• Exception handlers (@ControllerAdvice)
• Spring Security filters (if on classpath)
• Validation (if on classpath)

Testing GET Endpoints

@Test
void shouldReturnOrder() {
  var order = new Order(1L, "PENDING", BigDecimal.valueOf(99.99));
  given(orderService.findById(1L)).willReturn(order);
  
  assertThat(mvc.get().uri("/orders/1"))
    .hasStatusOk()
    .hasContentType(MediaType.APPLICATION_JSON)
    .bodyJson()
    .extractingPath("$.status")
    .isEqualTo("PENDING");
}

Testing POST with Request Body

Using Text Blocks (Java 25)

@Test
void shouldCreateOrder() {
  given(orderService.create(any(OrderRequest.class))).willReturn(1L);
  
  var json = """
    {
      "product": "Product A",
      "quantity": 2
    }
    """;
  
  assertThat(mvc.post().uri("/orders")
    .contentType(MediaType.APPLICATION_JSON)
    .content(json))
    .hasStatus(HttpStatus.CREATED)
    .hasHeader("Location", "/orders/1");
}

Using Records

record OrderRequest(String product, int quantity) {}

@Test
void shouldCreateOrderWithRecord() {
  var request = new OrderRequest("Product A", 2);
  given(orderService.create(any())).willReturn(1L);
  
  assertThat(mvc.post().uri("/orders")
    .contentType(MediaType.APPLICATION_JSON)
    .content(json.write(request).getJson()))
    .hasStatus(HttpStatus.CREATED);
}

Testing Validation Errors

@Test
void shouldRejectInvalidOrder() {
  var invalidJson = """
    {
      "product": "",
      "quantity": -1
    }
    """;
  
  assertThat(mvc.post().uri("/orders")
    .contentType(MediaType.APPLICATION_JSON)
    .content(invalidJson))
    .hasStatus(HttpStatus.BAD_REQUEST)
    .bodyJson()
    .hasPath("$.errors");
}

Testing Query Parameters

@Test
void shouldFilterOrdersByStatus() {
  assertThat(mvc.get().uri("/orders?status=PENDING"))
    .hasStatusOk();
  
  verify(orderService).findByStatus(OrderStatus.PENDING);
}

Testing Path Variables

@Test
void shouldCancelOrder() {
  assertThat(mvc.put().uri("/orders/123/cancel"))
    .hasStatusOk();
  
  verify(orderService).cancel(123L);
}

Testing with Security

@Test
@WithMockUser(roles = "ADMIN")
void adminShouldDeleteOrder() {
  assertThat(mvc.delete().uri("/orders/1"))
    .hasStatus(HttpStatus.NO_CONTENT);
}

@Test
void anonymousUserShouldBeForbidden() {
  assertThat(mvc.delete().uri("/orders/1"))
    .hasStatus(HttpStatus.UNAUTHORIZED);
}

Multiple Controllers

@WebMvcTest({OrderController.class, ProductController.class})
class WebLayerTest {
  // Tests multiple controllers in one slice
}

Excluding Auto-Configuration

@WebMvcTest(OrderController.class)
@AutoConfigureMockMvc(addFilters = false) // Skip security filters
class OrderControllerWithoutSecurityTest {
  // Tests without security filters
}

Key Points

1. Always mock services with @MockitoBean
2. Use MockMvcTester for AssertJ-style assertions
3. Test HTTP semantics (status, headers, content-type)
4. Verify service method calls when side effects matter
5. Don't test business logic here - that's for unit tests
6. Leverage Java 25 text blocks for JSON payloads