Practical Testing: 테스트 코드 작성 방법 - Mock, 더 나은 테스트를 위한 구체적 조언

// MailService 클래스
// 클라이언트(MailSendClient)를 통해 메일을 보낸 후, 이를 성공적으로 전송했을 때 해당 이력을 mailSendHistoryRepository 을 통해 기록하는 역할을 수행
@RequiredArgsConstructor
@Service
public class MailService {
    private final MailSendClient mailSendClient;
    private final MailSendHistoryRepository mailSendHistoryRepository;
    public boolean sendMail(String fromEmail, String toEmail, String subject, String content) {
        boolean result = mailSendClient.sendEmail(fromEmail, toEmail, subject, content);
        if(result) {
            mailSendHistoryRepository.save(MailSendHistory.builder()
                    .fromEmail(fromEmail)
                    .toEmail(toEmail)
                    .subject(subject)
                    .content(content)
                    .build()
            );
            return true;
        }
        return false;
    }
}
// MailServiceTest
class MailServiceTest {

  @DisplayName("메일 전송 테스트")
  @Test
  void sendMail() {
    // given
    MailSendClient mailSendClient = Mockito.mock(MailSendClient.class);
    MailSendHistoryRepository mailSendHistoryRepository = Mockito.mock(MailSendHistoryRepository.class);

    MailService mailService = new MailService(mailSendClient, mailSendHistoryRepository);

    // Stubbing - Mock 객체에 원하는 행위를 정의하는 것
    when(mailSendClient.sendEmail(anyString(), anyString(), anyString(), anyString()))
            .thenReturn(true);

    // when
    boolean result = mailService.sendMail("", "", "", "");

    // then
    Assertions.assertThat(result).isTrue();
  }

}

@ExtendWith(MockitoExtension.class)
class MailServiceTest {
    @Mock
    private MailSendClient mailSendClient;
    @Mock
    private MailSendHistoryRepository mailSendHistoryRepository;

    @DisplayName("메일 전송 테스트")
    @Test
    void sendMail() {
        // given
        MailService mailService = new MailService(mailSendClient, mailSendHistoryRepository);

        // Stubbing - Mock 객체에 원하는 행위를 정의하는 것
        when(mailSendClient.sendEmail(anyString(), anyString(), anyString(), anyString()))
                .thenReturn(true);

        // when
        boolean result = mailService.sendMail("", "", "", "");

        // then
        Assertions.assertThat(result).isTrue();
        // mailSendHistoryRepository.save()가 1 번 호출되었는지를 검증
        Mockito.verify(mailSendHistoryRepository, times(1)).save(any(MailSendHistory.class));
    }

}

@ExtendWith(MockitoExtension.class)
class MailServiceTest {
    @Mock
    private MailSendClient mailSendClient;
    @Mock
    private MailSendHistoryRepository mailSendHistoryRepository;

    @InjectMocks
    private MailService mailService;
    @DisplayName("메일 전송 테스트")
    @Test
    void sendMail() {
        // given

        // Stubbing - Mock 객체에 원하는 행위를 정의하는 것
        when(mailSendClient.sendEmail(anyString(), anyString(), anyString(), anyString()))
                .thenReturn(true);

        // when
        boolean result = mailService.sendMail("", "", "", "");

        // then
        Assertions.assertThat(result).isTrue();
        // mailSendHistoryRepository.save()가 1 번 호출되었는지를 검증
        Mockito.verify(mailSendHistoryRepository, times(1)).save(any(MailSendHistory.class));
    }

}

// MailSendClient - sendMail, a, b, c 메서드가 구현되어 있음.
@Slf4j
@Component
public class MailSendClient {
  public boolean sendEmail(String fromEmail, String toEmail, String subject, String content) {
    log.info("메일 전송");
    throw new IllegalArgumentException("메일 전송");
  }

  public void a() {
    log.info("a");
  }
  public void b() {
    log.info("b");
  }

  public void c() {
    log.info("c");
  }
}

// MailService - a, b, c 기능을 그대로 사용하고 있음.
@RequiredArgsConstructor
@Service
public class MailService {

  private final MailSendClient mailSendClient;
  private final MailSendHistoryRepository mailSendHistoryRepository;
  public boolean sendMail(String fromEmail, String toEmail, String subject, String content) {
    boolean result = mailSendClient.sendEmail(fromEmail, toEmail, subject, content);
    if(result) {
      mailSendHistoryRepository.save(MailSendHistory.builder()
              .fromEmail(fromEmail)
              .toEmail(toEmail)
              .subject(subject)
              .content(content)
              .build()
      );
      mailSendClient.a();
      mailSendClient.b();
      mailSendClient.c();

      return true;
    }

    return false;
  }
}

// 

@ExtendWith(MockitoExtension.class)
class MailServiceTest {
    @Spy
    private MailSendClient mailSendClient;
    @Mock
    private MailSendHistoryRepository mailSendHistoryRepository;

    @InjectMocks
    private MailService mailService;
    @DisplayName("메일 전송 테스트")
    @Test
    void sendMail() {
        // given

//        // Stubbing - Mock 객체에 원하는 행위를 정의하는 것
//        when(mailSendClient.sendEmail(anyString(), anyString(), anyString(), anyString()))
//                .thenReturn(true);
        doReturn(true)
                .when(mailSendClient)
                .sendEmail(anyString(), anyString(), anyString(), anyString());

        // when
        boolean result = mailService.sendMail("", "", "", "");

        // then
        Assertions.assertThat(result).isTrue();
        // mailSendHistoryRepository.save()가 1 번 호출되었는지를 검증
        Mockito.verify(mailSendHistoryRepository, times(1)).save(any(MailSendHistory.class));
    }

}

@ExtendWith(MockitoExtension.class)
class MailServiceTest {
    @Mock
    private MailSendClient mailSendClient;
    @Mock
    private MailSendHistoryRepository mailSendHistoryRepository;

    @InjectMocks
    private MailService mailService;
    
    @DisplayName("메일 전송 테스트")
    @Test
    void sendMail() {
        // given - Stubbing
        Mockito.when(mailSendClient.sendEmail(anyString(), anyString(), anyString(), anyString()))
                .thenReturn(true);

        // when
        boolean result = mailService.sendMail("", "", "", "");

        // then
        Assertions.assertThat(result).isTrue();
        // mailSendHistoryRepository.save()가 1 번 호출되었는지를 검증
        Mockito.verify(mailSendHistoryRepository, times(1)).save(any(MailSendHistory.class));
    }

}

@ExtendWith(MockitoExtension.class)
class MailServiceTest {
    @DisplayName("메일 전송 테스트")
    @Test
    void sendMail() {
        // given
        // BDDMockito의 문법인 BDDMockito.given을 사용하면 BDD 스타일을 지킬 수 있다.
        BDDMockito.given(mailSendClient.sendEmail(anyString(), anyString(), anyString(), anyString()))
                .willReturn(true);

        // when
        boolean result = mailService.sendMail("", "", "", "");

        // then
        Assertions.assertThat(result).isTrue();
        // mailSendHistoryRepository.save()가 1 번 호출되었는지를 검증
        Mockito.verify(mailSendHistoryRepository, times(1)).save(any(MailSendHistory.class));
    }

}

// CafeKiosk
@Getter
public class CafeKiosk {
    public Order createOrder() {
            LocalDateTime currentDateTime = LocalDateTime.now();
            LocalTime currentTime = currentDateTime.toLocalTime();
            if(currentTime.isBefore(SHOP_OPEN_TIME) || currentTime.isAfter(SHOP_CLOSE_TIME)) {
                throw new IllegalArgumentException("주문 시간이 아닙니다. 관리자에게 문의하세요.");
            }
    
            return new Order(currentDateTime, beverages);
        }
		
    public Order createOrder(LocalDateTime currentDateTime) {
        LocalTime currentTime = currentDateTime.toLocalTime();
        if(currentTime.isBefore(SHOP_OPEN_TIME) || currentTime.isAfter(SHOP_CLOSE_TIME)) {
            throw new IllegalArgumentException("주문 시간이 아닙니다. 관리자에게 문의하세요.");
        }

        return new Order(currentDateTime, beverages);
    }
}

// CafeKioskTest
class CafeKioskTest {
    @Test
    void createOrder() {
      CafeKiosk cafeKiosk = new CafeKiosk();
      Americano americano = new Americano();
  
      cafeKiosk.add(americano);
  
      Order order = cafeKiosk.createOrder();
  
      assertThat(order.getBeverages()).hasSize(1);
      assertThat(order.getBeverages().get(0).getName()).isEqualTo("아메리카노");
    }
  
    @Test
    void createOrderWithCurrentTime() {
      CafeKiosk cafeKiosk = new CafeKiosk();
      Americano americano = new Americano();
  
      cafeKiosk.add(americano);
  
      Order order = cafeKiosk.createOrder(LocalDateTime.of(2023, 11, 30, 10, 0));
  
      assertThat(order.getBeverages()).hasSize(1);
      assertThat(order.getBeverages().get(0).getName()).isEqualTo("아메리카노");
    }
    
    @Test
    void createOrderOutsideOpenTime() {
      CafeKiosk cafeKiosk = new CafeKiosk();
      Americano americano = new Americano();
  
      cafeKiosk.add(americano);
  
      assertThatThrownBy(() -> cafeKiosk.createOrder(LocalDateTime.of(2023, 11, 30, 9, 59)))
              .isInstanceOf(IllegalArgumentException.class)
              .hasMessage("주문 시간이 아닙니다. 관리자에게 문의하세요.");
    }
}

// OrderServiceTest
class OrderServiceTest {
    @DisplayName("재고가 부족한 상품으로 주문을 생성하려는 경우 예외가 발생한다.")
    @Test
    void createOrderWithNoStock() {
        LocalDateTime registeredDateTime = LocalDateTime.now();
        // given
        Product product1 = createProduct(BOTTLE, "001", 1000);
        Product product2 = createProduct(BAKERY, "002", 3000);
        Product product3 = createProduct(HANDMADE, "003", 5000);
        productRepository.saveAll(List.of(product1, product2, product3));

        Stock stock1 = Stock.create("001", 2);
        Stock stock2 = Stock.create("002", 2);
        stock1.deductQuantity(1); // todo
        stockRepository.saveAll(List.of(stock1, stock2));


        OrderCreateServiceRequest request = OrderCreateServiceRequest.builder()
                .productNumbers(List.of("001", "001", "002", "003"))
                .build();

        // when & then
        assertThatThrownBy(() -> orderService.createOrder(request, registeredDateTime))
                .isInstanceOf(IllegalArgumentException.class)
                .hasMessage("재고가 부족한 상품이 있습니다.");
    }
}

@BeforeAll
static void beforeAll() {

}

@BeforeEach
void setUp() {
    
}

class ProductServiceTest {
    // 모든 필드 파라미터로 받는 Builder 메서드
    private Product createProduct(String productNumber, ProductType type, ProductSellingStatus sellingStatus, String name, int price) {
        Product product1 = Product.builder()
                .productNumber(productNumber)
                .type(type)
                .sellingStatus(sellingStatus)
                .name(name)
                .price(price)
                .build();
        return product1;
    }
    // 2. 불필요한 파라미터(name)를 제거한 Builder 메서드
    private Product createProduct(String productNumber, ProductType type, ProductSellingStatus sellingStatus, int price) {
        Product product1 = Product.builder()
                .productNumber(productNumber)
                .type(type)
                .sellingStatus(sellingStatus)
                .name("아메리카노")
                .price(price)
                .build();
        return product1;
    }
}

class OrderServiceTest {

    @Autowired
    private ProductRepository productRepository;

    @Autowired
    private OrderRepository orderRepository;

    @Autowired
    private OrderProductRepository orderProductRepository;

    @Autowired
    private StockRepository stockRepository;

    @Autowired
    private OrderService orderService;	
		@AfterEach
    void tearDown() {
        orderProductRepository.deleteAllInBatch();
        productRepository.deleteAllInBatch();
        orderRepository.deleteAllInBatch();
        stockRepository.deleteAllInBatch();
    }
}

class ProductTypeTest {
    @DisplayName("상품 타입이 재고 관련 타입인지를 체크한다.")
    @CsvSource({"HANDMADE,false", "BOTTLE,true", "BAKERY,true"})
    @ParameterizedTest
    void containsStockType3(ProductType productType, boolean expected) {
        // when
        boolean result = ProductType.containsStockType(productType);

        // then
        assertThat(result).isEqualTo(expected);
    }
}

class ProductTypeTest {
    private static Stream<Arguments> provideProductTypesForCheckingStockType() {
      return Stream.of(
              Arguments.of(ProductType.HANDMADE, false),
              Arguments.of(ProductType.BOTTLE, true),
              Arguments.of(ProductType.BAKERY, true)
      );
    }
  
    @DisplayName("상품 타입이 재고 관련 타입인지를 체크한다.")
    @MethodSource("provideProductTypesForCheckingStockType")
    @ParameterizedTest
    void containsStockType4(ProductType productType, boolean expected) {
      // when
      boolean result = ProductType.containsStockType(productType);
  
      // then
      assertThat(result).isEqualTo(expected);
    }
}

class DynamicTestEx {
      @DisplayName("")
      @TestFactory
      Collection<DynamicTest> dynamicTest() {
  
          return List.of(
                  DynamicTest.dynamicTest("", () -> {
  
                  }),
                  DynamicTest.dynamicTest("", () -> {
  
                  })
          );
      }
}

class StockTest {
      @DisplayName("재고 차감 시나리오")
      @TestFactory
      Collection<DynamicTest> stockDeductionDynamicTest() {
      // given
      Stock stock = Stock.create("001", 1);
  
      return List.of(
              DynamicTest.dynamicTest("재고를 주어진 개수만큼 차감할 수 있다.", () -> {
                // given
                int quantity = 1;
  
                // when
                stock.deductQuantity(quantity);
  
                // then
                assertThat(stock.getQuantity()).isZero();
  
              }),
              DynamicTest.dynamicTest("재고보다 많은 수의 수량으로 차감 시도하는 경우 예외가 발생한다.", () -> {
                // given
                int quantity = 1;
  
                // when & then
                assertThatThrownBy(() -> stock.deductQuantity(quantity))
                        .isInstanceOf(IllegalArgumentException.class)
                        .hasMessage("차감할 재고 수량이 없습니다.");
              })
      );
    }
}

// IntegrationTestSupport - 추상 클래스
package sample.cafekiosk.spring;

import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.ActiveProfiles;

@ActiveProfiles("test")
@SpringBootTest
public abstract class IntegrationTestSupport {

    @MockBean
    protected MailSendClient mailSendClient; // 대신 다른 클래스에 적용할 수 있도록 private -> protected 로 바꿔준다. 
}

// ProductServiceTest, OrderServiceTest, OrderStatisticsServiceTest -> IntegrationTestSupport 로부터 상속받음
class ProductServiceTest extends IntegrationTestSupport {
}
class OrderServiceTest extends IntegrationTestSupport {
}
class OrderStatisticsServiceTest extends IntegrationTestSupport {
}

// ControllerTestSupport - 추상 클래스
@WebMvcTest(controllers = {
        OrderController.class,
        ProductController.class
})
public abstract class ControllerTestSupport {

    @Autowired
    protected MockMvc mockMvc;

    @Autowired
    protected ObjectMapper objectMapper;

    @MockBean
    protected OrderService orderService;

    @MockBean
    protected ProductService productService;
}
// OrderControllerTest, ProductControllerTest
class OrderControllerTest extends ControllerTestSupport {
}

class ProductControllerTest extends ControllerTestSupport {
}