public void Delete_HeadTest() { //删除前1 2 3 4 5 node1.Delete(); //删除后 2 3 4 5 Assert.IsNull(node1.Next); Assert.IsNull(node2.Previous); //删除前 2 3 4 5 node2.Delete(); //删除后 3 4 5 Assert.IsNull(node2.Next); Assert.IsNull(node3.Previous); //删除前 3 4 5 node3.Delete(); //删除后 4 5 Assert.IsNull(node3.Next); Assert.IsNull(node4.Previous); //删除前 4 5 node4.Delete(); //删除后 5 Assert.IsNull(node4.Next); Assert.IsNull(node5.Previous); //最后一个无法被删除 node5.Delete(); Assert.IsNull(node5.Previous); Assert.IsNull(node5.Next); }