public void AddAfterTestTwo()
{
//建立了一个节点,把节点添加到链表里面，链表名字是list
DLinkedListNode node = new DLinkedListNode();
DLinkedList list = new DLinkedList(node);
//new了一个新节点，添加到链表node节点后面
DLinkedListNode node_1 = new DLinkedListNode();
list.AddAfter(node_1, node);
//new了一个新节点，添加到链表node节点后面
DLinkedListNode newNode = new DLinkedListNode();
list.AddAfter(newNode, node);
//链表的头部是node
Assert.That(list.Head, Is.EqualTo(node));
//node节点的下一个是newNode
Assert.That(node.Next, Is.EqualTo(newNode));
//newNode节点的下一个是node1
Assert.That(newNode.Previous, Is.EqualTo(node));
Assert.That(newNode.Next, Is.EqualTo(node_1));
Assert.That(node_1.Previous, Is.EqualTo(newNode));
//尾巴是node1
Assert.That(list.Tail, Is.EqualTo(node_1));
}