public async Task CheckoutBookReturnsBookNotFoundWhenBookIsNotInRepository()
        {
            var bookRepositoryMock = new Mock<IBookRepository>();
            bookRepositoryMock.Setup(b => b.GetBook(It.IsAny<int>()))
                .ReturnsAsync(null);

            var userServiceMock = new Mock<IUserService>();
            userServiceMock.Setup(s => s.UserId).Returns("test");
            userServiceMock.Setup(s => s.UserName).Returns("test");

            var bookService = new BooksService(bookRepositoryMock.Object, userServiceMock.Object);

            var result = await bookService.CheckOutBook(1);

            Assert.AreEqual(CheckedOutBookState.BookNotFound, result.State);
        }
        public async Task CheckoutBookReturnsSuccess()
        {
            var bookDTO = new BookDTO()
            {
                Author = "test",
                Available = true,
                BookId = 1,
                Title = "test"
            };
            bookDTO.PhysicalBooks = new List<PhysicalBook>() {
                new PhysicalBook() { BookId = bookDTO.BookId, Id=1, UserId = null}
                };
            var bookRepositoryMock = new Mock<IBookRepository>();
            bookRepositoryMock.Setup(b => b.GetBook(It.IsAny<int>()))
                .ReturnsAsync(bookDTO);
            bookRepositoryMock.Setup(b => b.GetCheckedOutBooks(It.IsAny<string>()))
                .ReturnsAsync(new List<CheckedOutBookDTO>()
                {
                    new CheckedOutBookDTO(),
                    new CheckedOutBookDTO()
                });

            var userServiceMock = new Mock<IUserService>();
            userServiceMock.Setup(s => s.UserId).Returns("test");
            userServiceMock.Setup(s => s.UserName).Returns("test");

            var bookService = new BooksService(bookRepositoryMock.Object, userServiceMock.Object);

            var result = await bookService.CheckOutBook(1);

            Assert.AreEqual(CheckedOutBookState.Success, result.State);
        }