@Repository
public class BookRepository {

	public Book save(Book book) {
		return null;
	}
}

@Service
public class Book Service {

	private BookRepository bookRepository;
	
	public BookService(BookRepository bookRepository) {
	this.bookRepository = bookRepository;
	}
}

@RunWith(SpringRunner.class)
public class BookServiceTest {

	@Mock
	BookRepository bookRepository;
	
	@Test
	public void save() {
	
		Book book = new Book();

		//bookRepository.save(book)를 호출할 때 book을 리턴해줌
		when(bookRepository.save(book)).thenReturn(book);
		BookService bookService = new BookService(bookRepository);
		
		Book result = bookService.save(book);
		
		assertThat(Book.getCreated()).isNotNull();
		assertThat(book.getBookStatus()).isEqualTo(BookStatus.DRAFT);
		assertThat(result).isNotNull();
	}

}