I have problems with the delete method in Mockito

Question

public class BookControllerTest {
    int ID=2;
    int RELEASE=22;
    String AUTHOR="HOMERO";
    String TITLE="LA ODISEA";
    Book BOOK = new Book();
    Optional<Book> OPTIONAL_BOOK = Optional.of(BOOK);
    List<Review>REVIEW_LIST = new ArrayList<>();
    Optional<Book> OPTIONAL_BOOK_EMPTY = Optional.empty();
    /*Optional<Book> OPTIONAL_BOOK_DELETE = Optional.deleted();->error*/
    
    @Mock
    private BookRepository bookRepository;
    @InjectMocks
    private BookController bookController;
        
    ...

    @Test
    public void testDeleteBook() {
        Mockito.when(bookRepository.findById(ID)).thenReturn(OPTIONAL_BOOK_DELETE);
        ResponseEntity<Object> httpresponse = bookController.deleteBook(ID);
        assertEquals(HttpStatus.OK, httpresponse.getStatusCode());
    }
    
    @Test
    public void testDeleteBookNotFound() {
        Mockito.when(bookRepository.findById(ID)).thenReturn(OPTIONAL_BOOK_EMPTY);
        ResponseEntity<Object> httpresponse = bookController.deleteBook(ID);
        assertEquals(HttpStatus.NOT_FOUND, httpresponse.getStatusCode());
    }

}

I am new to this, would you be very kind, where is the error or what is the correct way?, I thought I could do the same as the empty method but I tried all the reserved words but it didn't work for me

Answer 1

Optional is a SDK class introduced with Java 8 and defines a fixed set of methods (cf. JavaDoc). You cannot "invent" your own methods on it and expect them to magically work. java.util.Optional is in no way dependent on your services.

If you have an optional without value, that's Optional.empty(). If you have an optional with a value, that's Optional.of(…). So deleting a book would still use Optional.empty(). Same as your bookNotFound test uses Optional.empty() and not Optional.notFound().

(Answer too long for a comment, but I'd rather have this question closed as "typo".)