testing

name	testing
description	JUnit and WebMvcTest patterns for the Spring MVC demo. Use when writing any new test or adding coverage.

Skill: Testing (spring-mvc-demo)

Service tests (plain JUnit, no Spring)

class ProductServiceTest {
    private ProductService service;

    @BeforeEach
    void setUp() {
        service = new ProductService();  // fresh store per test
    }
}

Controller tests (@WebMvcTest)

@WebMvcTest(ProductController.class)
class ProductControllerTest {
    @Autowired MockMvc mockMvc;
    @Autowired ObjectMapper objectMapper;
    @MockBean ProductService productService;
}

Rules

• Service tests: no Spring context, new ProductService() in @BeforeEach.
• Controller tests: @WebMvcTest only — no @SpringBootTest.
• Mock the service with @MockBean, never instantiate it in controller tests.
• Assert $.code in error responses — never $.message.
• Use willThrow(new XxxException(id)).given(service).method(id) for void methods.

Test naming

method_condition_expectedResult

Design Constraints

• Do not use @SpringBootTest — @WebMvcTest for controllers, plain JUnit for services
• Do not assert on $.message text — assert on $.code only
• Do not share service state between tests — always new ProductService() in @BeforeEach