public async Task AddBook()
        {
            BookModel book = new BookModel
            {
                Authors       = "Test Case Author",
                Name          = "Name Of Test Book",
                NumberOfPages = 10
            };
            var result = await _bookService.AddorUpdateBookAsync(book);

            var okResult = result.Should().BeOfType <ApiResponse <bool> >().Subject;

            okResult.StatusCode.Should().Be((int)HttpStatusCode.OK);
            okResult.Data.Should().Be(true);
        }