public void BinarySearchTree_InsertDuplicateKey_ReturnsFalse()
        {
            var tree = new Solution.BinarySearchTree();

            tree.Insert(5).Should().BeTrue();
            tree.Insert(5).Should().BeFalse();
        }
        public void BinarySearchTree_InsertKey_ReturnsTrue()
        {
            var tree = new Solution.BinarySearchTree();

            tree.Insert(5).Should().BeTrue();
            tree.Insert(3).Should().BeTrue();
            tree.Insert(4).Should().BeTrue();
        }
        public void BinarySearchTree_DeleteKey_ReturnsTrue()
        {
            var tree = new Solution.BinarySearchTree();

            tree.Insert(5);
            tree.Insert(8);
            tree.Insert(6);
            tree.Insert(4);
            tree.Delete(6).Should().BeTrue();
        }