Web Layer Tests with @WebMvcTest and MockMvc

@WebMvcTest(ProductController.class) starts only the MVC slice (controllers, advice, JSON, security filters) and provides MockMvc (or MockMvcTester with AssertJ). Mock services with @MockitoBean (replacing the deprecated @MockBean). Test status codes, JSON bodies, validation errors and authorization rules (spring-security-test adds jwt() and @WithMockUser).

@WebMvcTest(ProductController.class)
class ProductControllerTest {
    @Autowired MockMvc mvc;
    @MockitoBean ProductService products;

    @Test
    void returns404ProblemDetailForUnknownProduct() throws Exception {
        when(products.get(42)).thenThrow(new NotFoundException("Product 42 not found"));

        mvc.perform(get("/api/v1/products/42"))
           .andExpect(status().isNotFound())
           .andExpect(content().contentType(MediaType.APPLICATION_PROBLEM_JSON))
           .andExpect(jsonPath("$.detail").value("Product 42 not found"));
    }

    @Test
    void rejectsInvalidCreateRequest() throws Exception {
        mvc.perform(post("/api/v1/products").with(jwt().authorities(new SimpleGrantedAuthority("ROLE_ADMIN")))
                .contentType(MediaType.APPLICATION_JSON)
                .content("{\"name\": \"\", \"priceCents\": -1, \"currency\": \"USD\"}"))
           .andExpect(status().isBadRequest());
    }
}

Common pitfalls

• Loading the full context when only the web layer matters.
• Not testing security rules (unauthenticated → 401, wrong role → 403).
• Asserting on whole JSON strings that break on field order.

Key points

• @WebMvcTest loads only MVC
• @MockitoBean for service mocks
• Test validation, errors and security

Further reading: Spring Boot: Spring MVC tests