Remove manual validation once Controller validation (@Valid) is implemented.

Author: codesungrape

src/main/java/com/codesungrape/hmcts/bookapi/service/BookService.java

@@ -4,6 +4,7 @@
 import com.codesungrape.hmcts.bookapi.entity.Book;
 import com.codesungrape.hmcts.bookapi.exception.ResourceNotFoundException;
 import com.codesungrape.hmcts.bookapi.repository.BookRepository;
+import jakarta.transaction.Transactional;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
 
@@ -27,13 +28,14 @@ public class BookService {
      * @throws NullPointerException     if request is null
      * @throws IllegalArgumentException if title is null or blank
      */
+    @Transactional // Required: This method modifies data
     public Book createBook(BookRequest request) {
         // Validation check for business rules (e.g., uniqueness, if required)
         if (request == null) {
             throw new NullPointerException("BookRequest cannot be null");
         }
 
-        // TODO: Leaving this here for now as i haven't implemented the Controller Layer yet
+        // TODO: Remove manual validation once Controller validation (@Valid) is implemented.
         // The service layer is duplicating validation that already exists in the
         // BookRequest DTO with @notblank annotations. Since the DTO has validation
         // constraints, this manual check is redundant when Spring's validation
@@ -59,6 +61,7 @@ public Book createBook(BookRequest request) {
     }
 
     // Soft Delete
+    @Transactional // Required: This method modifies data
     public void deleteBookById(UUID bookId) {
 
         // find the book only if it's not already soft-deleted

src/test/java/com/codesungrape/hmcts/bookapi/BookServiceTest.java

@@ -140,13 +140,6 @@ void testCreateBook_Success() {
         verify(testBookRepository, times(1)).save(any(Book.class));
     }
 
-    // CoPilot feedback:
-    // This test will fail because BookRequest uses @value from Lombok with @notblank validation.
-    // The @notblank constraint on the title field means that creating a BookRequest with a null
-    // title should trigger validation failure at the DTO level, not allow the object to be
-    // created. Either the test expectations are incorrect, or the DTO validation is not being
-    // applied. The same issue affects tests on lines 105-116, 119-127, and 130-138.
-
     @Test
     void testCreateBook_NullRequest_ThrowsException() {
         // Act & Assert