public void Can_inorder_big_traverse()
        {
            // Arrange
            BinarySearchTree <int> testTree = new BinarySearchTree <int>();

            testTree.Add(5);
            testTree.Add(9);
            testTree.Add(7);
            testTree.Add(1);
            testTree.Add(12);
            testTree.Add(2);
            IEnumerable <int> expected = new int[] { 1, 2, 5, 7, 9, 12 };


            // Act
            IEnumerable <int> actual = testTree.InOrder(testTree.ReturnRoot());

            // Assert
            Assert.Equal(expected, actual);
        }