public void InOrderTraversal()
        {
            BinaryTree aTree = new BinaryTree(4);

            //        4
            //       / \
            //      2   5
            //     / \   \
            //    1   3   7
            //           / \
            //          6   8

            aTree.addToTree(2);
            aTree.addToTree(5);
            aTree.addToTree(7);
            aTree.addToTree(3);
            aTree.addToTree(1);
            aTree.addToTree(6);
            aTree.addToTree(8);
            aTree.inOrder();
            int[] expected = { 1, 2, 3, 4, 5, 6, 7, 8 };
            int   index    = 0;

            foreach (int actual in aTree.Output)
            {
                Assert.AreEqual(expected[index++], actual);
            }
        }