    @Test
    public void shouldSaveNewUser_GivenThereDoesNotExistOneWithTheSameId_ThenTheSavedUserShouldBeReturned() throws Exception {

        final Book savedBook = stubRepositoryToReturnUserOnSave();
        final Book book = UserUtil.createBook();
        final Book returnedBook = bookService.saveBook(book);
        // verify repository was called with book
        verify(bookRepository, times(1)).save(book);
        assertEquals("Returned book should come from the repository", savedBook, returnedBook);
    }