public void TwoHop()
        {
            _bookAuthors.AddRange(
                new List <BookAuthor>
            {
                new BookAuthor
                {
                    AuthorId = 2,
                    BookId   = 1
                },
                new BookAuthor
                {
                    AuthorId = 3,
                    BookId   = 1
                },
                new BookAuthor
                {
                    AuthorId = 3,
                    BookId   = 2
                },
                new BookAuthor
                {
                    AuthorId = 1,
                    BookId   = 2
                }
            });

            _iErdosNumberBusinessService = new ErdosNumberBusinessService(_authors, _books, _bookAuthors);
            var hops = _iErdosNumberBusinessService.Hops("SomeAuthor");

            Assert.Equal(2, hops);
        }
        public void SingleHop()
        {
            _bookAuthors.Add(
                new BookAuthor
            {
                AuthorId = 2,
                BookId   = 1
            });

            _bookAuthors.Add(
                new BookAuthor
            {
                AuthorId = 1,
                BookId   = 1
            });
            _iErdosNumberBusinessService = new ErdosNumberBusinessService(_authors, _books, _bookAuthors);
            var hops = _iErdosNumberBusinessService.Hops("SomeAuthor");

            Assert.Equal(1, hops);
        }