# Chương 4: Kiểm thử đơn vị (Unit Test) Chương này hướng dẫn cách viết unit test cho API trong ứng dụng Java Spring Boot. Nội dung bao gồm cấu trúc test chuẩn, cách mock dependency, kiểm tra validate input, xác thực (authentication/authorization), ghi log, xử lý exception và kiểm tra logic service. Mục tiêu đảm bảo mỗi API hoạt động đúng, an toàn và ổn định trước khi tích hợp hoặc triển khai. # Nội dung chi tiết ## 1. Nguyên tắc Unit Test API Mỗi API cần test các nhóm case cơ bản: 1. Validate input 2. Auth / permission 3. Business logic 4. Repository interaction 5. Exception handling 6. Logging 7. HTTP status & response --- # 2. Ví dụ API mẫu Controller:
`@RestController@RequestMapping("/users")@RequiredArgsConstructorpublic class UserController { private final UserService userService; @PostMapping public ResponseEntity create( @Valid @RequestBody CreateUserRequest req) { return ResponseEntity.ok(userService.create(req)); }}`
DTO:
`@Datapublic class CreateUserRequest { @NotBlank private String username; @Email private String email;}`
Service:
`@Service@RequiredArgsConstructorpublic class UserService { private final UserRepository repo; public UserResponse create(CreateUserRequest req) { User u = new User(req.getUsername(), req.getEmail()); repo.save(u); return new UserResponse(u.getId(), u.getUsername()); }}`
--- # 3. Cấu trúc test chuẩn Dependency:
`<dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-testartifactId> <scope>testscope>dependency>`
Controller test dùng: - @WebMvcTest - MockMvc - @MockBean --- # 4. Test Validate Input Case cần có: - thiếu field bắt buộc - email sai format - request null
`@WebMvcTest(UserController.class)class UserControllerValidationTest { @Autowired private MockMvc mockMvc; @MockBean private UserService userService; @Test void create_shouldFail_whenUsernameBlank() throws Exception { String json = """ {"username":"","email":"a@test.com"} """; mockMvc.perform(post("/users") .contentType(MediaType.APPLICATION_JSON) .content(json)) .andExpect(status().isBadRequest()); } @Test void create_shouldFail_whenEmailInvalid() throws Exception { String json = """ {"username":"john","email":"invalid"} """; mockMvc.perform(post("/users") .contentType(MediaType.APPLICATION_JSON) .content(json)) .andExpect(status().isBadRequest()); }}`
--- # 5. Test Auth / Permission Giả sử API cần login:
`@WithMockUser@Testvoid create_shouldSuccess_whenAuthenticated() throws Exception { when(userService.create(any())) .thenReturn(new UserResponse(1L,"john")); String json = """ {"username":"john","email":"a@test.com"} """; mockMvc.perform(post("/users") .contentType(MediaType.APPLICATION_JSON) .content(json)) .andExpect(status().isOk());}`
Test chưa login:
`@Testvoid create_shouldUnauthorized_whenNoAuth() throws Exception { String json = """ {"username":"john","email":"a@test.com"} """; mockMvc.perform(post("/users") .contentType(MediaType.APPLICATION_JSON) .content(json)) .andExpect(status().isUnauthorized());}`
--- # 6. Test Business Logic (Service)
`@ExtendWith(MockitoExtension.class)class UserServiceTest { @Mock private UserRepository repo; @InjectMocks private UserService service; @Test void create_shouldSaveUser() { CreateUserRequest req = new CreateUserRequest(); req.setUsername("john"); req.setEmail("a@test.com"); when(repo.save(any())).thenAnswer(i -> i.getArgument(0)); UserResponse res = service.create(req); assertEquals("john", res.getUsername()); verify(repo).save(any()); }}`
--- # 7. Test Exception Handling Giả sử email trùng:
`when(repo.save(any())) .thenThrow(new DataIntegrityViolationException("dup"));`
Test:
`@Testvoid create_shouldThrow_whenDuplicateEmail() { CreateUserRequest req = new CreateUserRequest(); req.setUsername("john"); req.setEmail("a@test.com"); when(repo.save(any())) .thenThrow(new RuntimeException("duplicate")); assertThrows(RuntimeException.class, () -> service.create(req));}`
--- # 8. Test Logging Giả sử service có log:
`log.info("Create user {}", req.getUsername());`
Test log:
`@ExtendWith(MockitoExtension.class)class UserServiceLogTest { @Mock private UserRepository repo; @InjectMocks private UserService service; @Test void create_shouldLog() { CreateUserRequest req = new CreateUserRequest(); req.setUsername("john"); req.setEmail("a@test.com"); when(repo.save(any())).thenAnswer(i -> i.getArgument(0)); service.create(req); verify(repo).save(any()); }}`
(Thực tế có thể dùng LogCaptor) --- # 9. Test HTTP Response
`@Test@WithMockUservoid create_shouldReturnBody() throws Exception { when(userService.create(any())) .thenReturn(new UserResponse(1L,"john")); String json = """ {"username":"john","email":"a@test.com"} """; mockMvc.perform(post("/users") .contentType(MediaType.APPLICATION_JSON) .content(json)) .andExpect(status().isOk()) .andExpect(jsonPath("$.username").value("john"));}`
--- # 10. Danh sách Case chuẩn cho mỗi API Mỗi API cần tối thiểu: ### Validate - [ ] [ ] thiếu field - [ ] [ ] format sai - [ ] [ ] null body ### Auth - [ ] [ ] chưa login - [ ] [ ] sai role - [ ] [ ] đúng role ### Business - [ ] [ ] flow thành công - [ ] [ ] dữ liệu biên - [ ] [ ] điều kiện đặc biệt ### Repository - [ ] [ ] save OK - [ ] [ ] not found - [ ] [ ] duplicate ### Exception - [ ] [ ] DB lỗi - [ ] [ ] logic lỗi - [ ] [ ] external lỗi ### Response - [ ] [ ] status code - [ ] [ ] body - [ ] [ ] schema ### Log - [ ] [ ] log khi success - [ ] [ ] log khi error --- # 11. Checklist Unit Test API - [ ] [ ] Test validate - [ ] [ ] Test auth - [ ] [ ] Test service - [ ] [ ] Mock repo - [ ] [ ] Test exception - [ ] [ ] Test response - [ ] [ ] Verify interaction - [ ] [ ] No DB thật - [ ] [ ] No network