Evaluation Article: A quick and practical example of Hexagonal Architecture in Java

ddd/src/main/java/com/baeldung/hexagonal/HexagonalSpringApplication.java

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+package com.baeldung.hexagonal;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration;
+import org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration;
+import org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration;
+
+
+@SpringBootApplication(exclude={
+        CassandraAutoConfiguration.class,
+        MongoDataAutoConfiguration.class,
+        MongoAutoConfiguration.class
+})
+public class HexagonalSpringApplication {
+
+    public static void main(final String[] args) {
+        SpringApplication.run(HexagonalSpringApplication.class, args);
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/adapter/BookingPersistenceAdapter.java

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+package com.baeldung.hexagonal.adapter;
+
+import com.baeldung.hexagonal.domain.Booking;
+import com.baeldung.hexagonal.port.BookingPersistencePort;
+import com.baeldung.hexagonal.repository.BookingRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class BookingPersistenceAdapter implements BookingPersistencePort {
+
+    @Autowired
+    private BookingRepository bookingRepository;
+
+    public boolean persist(Booking booking) {
+        return bookingRepository.save(booking);
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/adapter/RestAPIEndpointAdapter.java

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+package com.baeldung.hexagonal.adapter;
+
+import com.baeldung.hexagonal.port.BookingServicePort;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RestController;
+
+import static com.baeldung.hexagonal.port.BookingServicePort.BookingRequest;
+import static com.baeldung.hexagonal.port.BookingServicePort.BookingResponse;
+import static com.baeldung.hexagonal.port.BookingServicePort.BookingResponse.*;
+
+@RestController
+public class RestAPIEndpointAdapter {
+
+    private BookingServicePort bookingServicePort;
+
+    @Autowired
+    public RestAPIEndpointAdapter(BookingServicePort bookingServicePort) {
+        this.bookingServicePort = bookingServicePort;
+    }
+
+    @PostMapping(path = "/booking")
+    public ResponseEntity<BookingResponse> createBooking(@RequestBody BookingRequest request) {
+        BookingResponse response = bookingServicePort.book(request);
+
+        if (response.getStatusCode() == SEAT_NOT_AVAILABLE
+                    || response.getStatusCode() == PAYMENT_FAILED){
+            return new ResponseEntity<BookingResponse>(response, HttpStatus.PRECONDITION_FAILED);
+        } else if (response.getStatusCode() == UNKNOWN_ERROR) {
+            return new ResponseEntity<BookingResponse>(response, HttpStatus.INTERNAL_SERVER_ERROR);
+        }
+
+        return new ResponseEntity<BookingResponse>(response, HttpStatus.CREATED);
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/adapter/TheatreServiceAdapter.java

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+package com.baeldung.hexagonal.adapter;
+
+import com.baeldung.hexagonal.external.service.TheatreService;
+import com.baeldung.hexagonal.port.TheatreServicePort;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Component;
+
+import java.util.Optional;
+import java.util.Set;
+
+@Component
+public class TheatreServiceAdapter implements TheatreServicePort {
+
+    @Autowired
+    private TheatreService theatreService;
+
+    public Optional<String> reserveSeats(String theatreId, String movieShowId, Set<String> seats) {
+        ResponseEntity<TheatreService.Reservation> response = theatreService.postReservation(theatreId, movieShowId, seats);
+        if (response.getStatusCode() == HttpStatus.CREATED) {
+            return Optional.of(response.getBody().getId());
+        }
+        return Optional.empty();
+    }
+
+    public boolean releaseSeats(String resrevationId) {
+        ResponseEntity<?> response = theatreService.deleteReservation(resrevationId);
+        return response.getStatusCode() == HttpStatus.NO_CONTENT;
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/adapter/WalletServiceAdapter.java

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+package com.baeldung.hexagonal.adapter;
+
+import com.baeldung.hexagonal.external.service.CustomerWalletService;
+import com.baeldung.hexagonal.port.WalletServicePort;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Component;
+
+@Component
+public class WalletServiceAdapter implements WalletServicePort {
+
+    private final CustomerWalletService customerWalletService;
+
+    @Autowired
+    public WalletServiceAdapter(CustomerWalletService customerWalletService) {
+        this.customerWalletService = customerWalletService;
+    }
+
+    public boolean debit(String customerId, Double amount) {
+        HttpStatus response = customerWalletService.postDebit(customerId, amount);
+        return response == HttpStatus.CREATED;
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/domain/Booking.java

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+package com.baeldung.hexagonal.domain;
+
+import java.util.Set;
+
+public class Booking {
+    private String bookingId;
+    private String movieShowId;
+    private String theatreId;
+    private String customerId;
+    private Set<String> seats;
+    private Double amount;
+    private Status status;
+
+    public enum Status {
+        INITIAL, SUCCESS, FAILURE
+    }
+
+    public Booking(
+            String bookingId, String movieShowId, String theatreId, String customerId, Set<String> seats, Double amount, Status status) {
+        this.bookingId = bookingId;
+        this.movieShowId = movieShowId;
+        this.theatreId = theatreId;
+        this.customerId = customerId;
+        this.seats = seats;
+        this.amount = amount;
+        this.status = Status.INITIAL;
+    }
+
+    public String getMovieShowId() {
+        return movieShowId;
+    }
+
+    public String getTheatreId() {
+        return theatreId;
+    }
+
+    public Set<String> getSeats() {
+        return seats;
+    }
+
+    public String getCustomerId() {
+        return customerId;
+    }
+
+    public String getBookingId() {
+        return bookingId;
+    }
+
+    public Double getAmount() {
+        return amount;
+    }
+
+    public Status getStatus() {
+        return status;
+    }
+
+    public void setBookingId(String bookingId) {
+        this.bookingId = bookingId;
+    }
+
+    public void setMovieShowId(String movieShowId) {
+        this.movieShowId = movieShowId;
+    }
+
+    public void setTheatreId(String theatreId) {
+        this.theatreId = theatreId;
+    }
+
+    public void setCustomerId(String customerId) {
+        this.customerId = customerId;
+    }
+
+    public void setSeats(Set<String> seats) {
+        this.seats = seats;
+    }
+
+    public void setAmount(Double amount) {
+        this.amount = amount;
+    }
+
+    public void setStatus(Status status) {
+        this.status = status;
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/external/service/CustomerWalletService.java

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+package com.baeldung.hexagonal.external.service;
+
+import org.springframework.http.HttpStatus;
+
+public interface CustomerWalletService {
+
+    HttpStatus postDebit(String customerId, Double amount);
+}

ddd/src/main/java/com/baeldung/hexagonal/external/service/MockCustomerWalletService.java

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+package com.baeldung.hexagonal.external.service;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Service;
+
+@Service
+public class MockCustomerWalletService implements CustomerWalletService {
+    public HttpStatus postDebit(String customerId, Double amount) {
+        return HttpStatus.CREATED;
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/external/service/MockTheatreService.java

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+package com.baeldung.hexagonal.external.service;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Service;
+
+import java.util.Set;
+import java.util.UUID;
+
+@Service
+public class MockTheatreService implements TheatreService {
+
+    public ResponseEntity<Reservation> postReservation(String theatreId, String movieShowId, Set<String> seats) {
+        return new ResponseEntity<Reservation>(
+                new Reservation(UUID.randomUUID().toString()), HttpStatus.CREATED);
+    }
+
+    public ResponseEntity<?> deleteReservation(String reservationId) {
+        return new ResponseEntity(HttpStatus.NO_CONTENT);
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/external/service/TheatreService.java

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+package com.baeldung.hexagonal.external.service;
+
+import org.springframework.http.ResponseEntity;
+
+import java.util.Set;
+
+public interface TheatreService {
+
+    ResponseEntity<Reservation> postReservation(String theatreId, String movieShowId, Set<String> seats);
+
+    ResponseEntity<?> deleteReservation(String reservationId);
+
+    class Reservation {
+        private final String id;
+
+        public Reservation(String id) {
+            this.id = id;
+        }
+
+        public String getId() {
+            return id;
+        }
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/port/BookingPersistencePort.java

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+package com.baeldung.hexagonal.port;
+
+import com.baeldung.hexagonal.domain.Booking;
+
+public interface BookingPersistencePort {
+    boolean persist(Booking booking);
+}

ddd/src/main/java/com/baeldung/hexagonal/port/BookingServicePort.java

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+package com.baeldung.hexagonal.port;
+
+import java.util.Set;
+
+public interface BookingServicePort {
+
+    BookingResponse book(BookingRequest request);
+
+    class BookingRequest {
+        private String movieShowId;
+        private String customerId;
+        private String theatreId;
+        private Set<String> seats;
+        private Double amount;
+
+        public String getMovieShowId() {
+            return movieShowId;
+        }
+
+        public void setMovieShowId(String movieShowId) {
+            this.movieShowId = movieShowId;
+        }
+
+        public String getCustomerId() {
+            return customerId;
+        }
+
+        public void setCustomerId(String customerId) {
+            this.customerId = customerId;
+        }
+
+        public String getTheatreId() {
+            return theatreId;
+        }
+
+        public void setTheatreId(String theatreId) {
+            this.theatreId = theatreId;
+        }
+
+        public Set<String> getSeats() {
+            return seats;
+        }
+
+        public void setSeats(Set<String> seats) {
+            this.seats = seats;
+        }
+
+        public Double getAmount() {
+            return amount;
+        }
+
+        public void setAmount(Double amount) {
+            this.amount = amount;
+        }
+    }
+
+    class BookingResponse {
+        public static final int SUCCESS = 0;
+        public static final int SEAT_NOT_AVAILABLE = 1;
+        public static final int PAYMENT_FAILED = 2;
+        public static final int UNKNOWN_ERROR = 3;
+
+        private final int statusCode;
+
+        public BookingResponse(int statusCode) {
+            this.statusCode = statusCode;
+        }
+
+        public int getStatusCode() {
+            return statusCode;
+        }
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/port/TheatreServicePort.java

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+package com.baeldung.hexagonal.port;
+
+import java.util.Optional;
+import java.util.Set;
+
+public interface TheatreServicePort {
+    Optional<String> reserveSeats(String theatreId, String movieShowId, Set<String> seats);
+    boolean releaseSeats(String resrevationId);
+}

ddd/src/main/java/com/baeldung/hexagonal/port/WalletServicePort.java

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+package com.baeldung.hexagonal.port;
+
+public interface WalletServicePort {
+    boolean debit(String customerId, Double amount);
+}

ddd/src/main/java/com/baeldung/hexagonal/repository/BookingRepository.java

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+package com.baeldung.hexagonal.repository;
+
+import com.baeldung.hexagonal.domain.Booking;
+
+public interface BookingRepository {
+
+    boolean save(Booking booking);
+}

ddd/src/main/java/com/baeldung/hexagonal/repository/MockBookingRepository.java

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+package com.baeldung.hexagonal.repository;
+
+import com.baeldung.hexagonal.domain.Booking;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public class MockBookingRepository implements BookingRepository {
+    public boolean save(Booking booking) {
+        return true;
+    }
+}

ddd/src/main/java/com/baeldung/hexagonal/usecase/BookTicketUseCase.java

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+package com.baeldung.hexagonal.usecase;
+
+import com.baeldung.hexagonal.domain.Booking;
+import com.baeldung.hexagonal.port.BookingPersistencePort;
+import com.baeldung.hexagonal.port.BookingServicePort;
+import com.baeldung.hexagonal.port.TheatreServicePort;
+import com.baeldung.hexagonal.port.WalletServicePort;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import java.util.Optional;
+import java.util.UUID;
+
+import static com.baeldung.hexagonal.port.BookingServicePort.BookingResponse.*;
+
+@Component
+public class BookTicketUseCase implements BookingServicePort {
+
+    private BookingPersistencePort bookingPersistencePort;
+    private TheatreServicePort theatreServicePort;
+    private WalletServicePort walletServicePort;
+
+    @Autowired
+    public BookTicketUseCase(BookingPersistencePort bookingPersistencePort, TheatreServicePort theatreServicePort, WalletServicePort walletServicePort) {
+        this.bookingPersistencePort = bookingPersistencePort;
+        this.theatreServicePort = theatreServicePort;
+        this.walletServicePort = walletServicePort;
+    }
+
+    public BookingResponse book(BookingRequest request) {
+
+        Booking booking = new Booking(
+                            UUID.randomUUID().toString(),
+                            request.getMovieShowId(),
+                            request.getTheatreId(),
+                            request.getCustomerId(),
+                            request.getSeats(),
+                            request.getAmount(),
+                            Booking.Status.INITIAL);
+
+        if (!bookingPersistencePort.persist(booking)) {
+            return new BookingResponse(UNKNOWN_ERROR);
+        }
+
+        Optional<String> reservationIdOptional = theatreServicePort.reserveSeats(
+                booking.getTheatreId(),
+                booking.getMovieShowId(),
+                booking.getSeats());
+        if (!reservationIdOptional.isPresent()) {
+            booking.setStatus(Booking.Status.FAILURE);
+            bookingPersistencePort.persist(booking);
+            return new BookingResponse(SEAT_NOT_AVAILABLE);
+        }
+
+        if (!walletServicePort.debit(booking.getCustomerId(), booking.getAmount())) {
+            reservationIdOptional.ifPresent(reservationId -> theatreServicePort.releaseSeats(reservationId));
+            booking.setStatus(Booking.Status.FAILURE);
+            bookingPersistencePort.persist(booking);
+            return new BookingResponse(PAYMENT_FAILED);
+        }
+
+        booking.setStatus(Booking.Status.SUCCESS);
+        bookingPersistencePort.persist(booking);
+
+        return new BookingResponse(SUCCESS);
+    }
+}

ddd/src/test/java/com/baeldung/hexagonal/adapter/RestAPIEndpointAdapterUnitTest.java

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+package com.baeldung.hexagonal.adapter;
+
+import com.baeldung.hexagonal.port.BookingServicePort;
+import com.baeldung.hexagonal.port.BookingServicePort.BookingRequest;
+import com.baeldung.hexagonal.port.BookingServicePort.BookingResponse;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+
+import java.util.Arrays;
+import java.util.HashSet;
+
+import static com.baeldung.hexagonal.port.BookingServicePort.BookingResponse.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+class RestAPIEndpointAdapterUnitTest {
+
+    private BookingServicePort bookingServicePort;
+    private RestAPIEndpointAdapter restAPIEndpointAdapter;
+
+    @BeforeEach
+    void setUp() {
+        bookingServicePort = mock(BookingServicePort.class);
+        restAPIEndpointAdapter = new RestAPIEndpointAdapter(bookingServicePort);
+    }
+
+    private BookingServicePort.BookingRequest getBookingRequest() {
+        BookingServicePort.BookingRequest request = new BookingServicePort.BookingRequest();
+        request.setTheatreId("theatre-id");
+        request.setMovieShowId("movie-show-id");
+        request.setCustomerId("customer-id");
+        request.setSeats(new HashSet<>(Arrays.asList("A1", "A2")));
+        request.setAmount(100.00);
+        return request;
+    }
+
+    @Test
+    void whenBookingServicePortReturnsUnknownError_thenReturnInternalServerError() {
+        BookingServicePort.BookingRequest request = getBookingRequest();
+        when(bookingServicePort.book(any(BookingRequest.class))).thenReturn(new BookingResponse(UNKNOWN_ERROR));
+
+        ResponseEntity<BookingResponse> response = restAPIEndpointAdapter.createBooking(request);
+
+        verify(bookingServicePort).book(any(BookingRequest.class));
+        assertNotNull(response);
+        assertEquals(HttpStatus.INTERNAL_SERVER_ERROR, response.getStatusCode());
+    }
+
+    @Test
+    void whenBookingServicePortReturnsSeatUnavailable_thenReturnPreconditionFailed() {
+        BookingServicePort.BookingRequest request = getBookingRequest();
+        when(bookingServicePort.book(any(BookingRequest.class))).thenReturn(new BookingResponse(SEAT_NOT_AVAILABLE));
+
+        ResponseEntity<BookingResponse> response = restAPIEndpointAdapter.createBooking(request);
+
+        verify(bookingServicePort).book(any(BookingRequest.class));
+        assertNotNull(response);
+        assertEquals(HttpStatus.PRECONDITION_FAILED, response.getStatusCode());
+    }
+
+    @Test
+    void whenBookingServicePortReturnsPaymentFailed_thenReturnPreconditionFailed() {
+        BookingServicePort.BookingRequest request = getBookingRequest();
+        when(bookingServicePort.book(any(BookingRequest.class))).thenReturn(new BookingResponse(PAYMENT_FAILED));
+
+        ResponseEntity<BookingResponse> response = restAPIEndpointAdapter.createBooking(request);
+
+        verify(bookingServicePort).book(any(BookingRequest.class));
+        assertNotNull(response);
+        assertEquals(HttpStatus.PRECONDITION_FAILED, response.getStatusCode());
+    }
+
+    @Test
+    void whenBookingServicePortReturnsSuccess_thenReturnCreated() {
+        BookingServicePort.BookingRequest request = getBookingRequest();
+        when(bookingServicePort.book(any(BookingRequest.class))).thenReturn(new BookingResponse(SUCCESS));
+
+        ResponseEntity<BookingResponse> response = restAPIEndpointAdapter.createBooking(request);
+
+        verify(bookingServicePort).book(any(BookingRequest.class));
+        assertNotNull(response);
+        assertEquals(HttpStatus.CREATED, response.getStatusCode());
+    }
+}

ddd/src/test/java/com/baeldung/hexagonal/usecase/BookTicketUseCaseUnitTest.java

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+package com.baeldung.hexagonal.usecase;
+
+import com.baeldung.hexagonal.domain.Booking;
+import com.baeldung.hexagonal.port.BookingPersistencePort;
+import com.baeldung.hexagonal.port.BookingServicePort;
+import com.baeldung.hexagonal.port.TheatreServicePort;
+import com.baeldung.hexagonal.port.WalletServicePort;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+class BookTicketUseCaseUnitTest {
+
+    private BookingPersistencePort bookingPersistencePort;
+    private TheatreServicePort theatreServicePort;
+    private WalletServicePort walletServicePort;
+    private BookTicketUseCase bookTicketUseCase;
+
+    @BeforeEach
+    void setUp() {
+        bookingPersistencePort = mock(BookingPersistencePort.class);
+        theatreServicePort = mock(TheatreServicePort.class);
+        walletServicePort = mock(WalletServicePort.class);
+        bookTicketUseCase = new BookTicketUseCase(bookingPersistencePort, theatreServicePort, walletServicePort);
+    }
+
+    private BookingServicePort.BookingRequest getBookingRequest() {
+        BookingServicePort.BookingRequest request = new BookingServicePort.BookingRequest();
+        request.setTheatreId("theatre-id");
+        request.setMovieShowId("movie-show-id");
+        request.setCustomerId("customer-id");
+        request.setSeats(new HashSet<>(Arrays.asList("A1", "A2")));
+        request.setAmount(100.00);
+        return request;
+    }
+
+    private Booking getBooking(BookingServicePort.BookingRequest request) {
+        return new Booking(
+                "booking-id",
+                request.getMovieShowId(),
+                request.getTheatreId(),
+                request.getCustomerId(),
+                request.getSeats(),
+                request.getAmount(),
+                Booking.Status.INITIAL);
+    }
+
+    @Test
+    void whenErrorInInitialPersistence_thenReturnUnknownError() {
+        BookingServicePort.BookingRequest request = getBookingRequest();
+        Booking booking = getBooking(request);
+        when(bookingPersistencePort.persist(any(Booking.class))).thenReturn(false);
+        BookingServicePort.BookingResponse response = bookTicketUseCase.book(request);
+
+        verify(bookingPersistencePort, times(1)).persist(any(Booking.class));
+        assertNotNull(response);
+        assertEquals(BookingServicePort.BookingResponse.UNKNOWN_ERROR, response.getStatusCode());
+    }
+
+    @Test
+    void whenErrorInReserveSeats_thenReturnSeatNotAvailable() {
+        BookingServicePort.BookingRequest request = getBookingRequest();
+        Booking booking = getBooking(request);
+        when(bookingPersistencePort.persist(any(Booking.class))).thenReturn(true);
+        when(theatreServicePort.reserveSeats(booking.getTheatreId(), booking.getMovieShowId(), booking.getSeats()))
+                .thenReturn(Optional.empty());
+        BookingServicePort.BookingResponse response = bookTicketUseCase.book(request);
+
+        verify(bookingPersistencePort, times(2)).persist(any(Booking.class));
+        verify(theatreServicePort).reserveSeats(any(String.class), any(String.class), any(HashSet.class));
+        assertNotNull(response);
+        assertEquals(BookingServicePort.BookingResponse.SEAT_NOT_AVAILABLE, response.getStatusCode());
+    }
+
+    @Test
+    void whenErrorInWalletDebit_thenReturnPaymentFailed() {
+        BookingServicePort.BookingRequest request = getBookingRequest();
+        Booking booking = getBooking(request);
+        when(bookingPersistencePort.persist(any(Booking.class))).thenReturn(true);
+        when(theatreServicePort.reserveSeats(booking.getTheatreId(), booking.getMovieShowId(), booking.getSeats()))
+                .thenReturn(Optional.of("reservation-id"));
+        when(walletServicePort.debit(booking.getCustomerId(), booking.getAmount()))
+                .thenReturn(false);
+        BookingServicePort.BookingResponse response = bookTicketUseCase.book(request);
+
+        verify(bookingPersistencePort, times(2)).persist(any(Booking.class));
+        verify(theatreServicePort).reserveSeats(any(String.class), any(String.class), any(HashSet.class));
+        verify(walletServicePort).debit(any(String.class), any(Double.class));
+        verify(theatreServicePort).releaseSeats(any(String.class));
+        assertNotNull(response);
+        assertEquals(BookingServicePort.BookingResponse.PAYMENT_FAILED, response.getStatusCode());
+    }
+
+    @Test
+    void whenNoErrorInAnyPorts_thenReturnSuccess() {
+        BookingServicePort.BookingRequest request = getBookingRequest();
+        Booking booking = getBooking(request);
+        when(bookingPersistencePort.persist(any(Booking.class))).thenReturn(true);
+        when(theatreServicePort.reserveSeats(booking.getTheatreId(), booking.getMovieShowId(), booking.getSeats()))
+                .thenReturn(Optional.of("reservation-id"));
+        when(walletServicePort.debit(booking.getCustomerId(), booking.getAmount()))
+                .thenReturn(true);
+        BookingServicePort.BookingResponse response = bookTicketUseCase.book(request);
+
+        verify(bookingPersistencePort, times(2)).persist(any(Booking.class));
+        verify(theatreServicePort).reserveSeats(any(String.class), any(String.class), any(HashSet.class));
+        verify(walletServicePort).debit(any(String.class), any(Double.class));
+        assertNotNull(response);
+        assertEquals(BookingServicePort.BookingResponse.SUCCESS, response.getStatusCode());
+    }
+}