Delete nodes with a given value from a doubly linked list

Delete all nodes that their values equals “foo” from a doubly linked list, your input is on of the nodes in the list

Tests:

        [TestMethod]
        public void TestDeleteNodesFromDoublyLInkedList()
        {
            var i4 = new DoublyLinkedItem("laa", null);
            var i3 = new DoublyLinkedItem("foo", i4);
            i4.Previous = i3;
            var i2 = new DoublyLinkedItem("laa", i3);
            i3.Previous = i2;
            var i1 = new DoublyLinkedItem("laa", i2);
            i2.Previous = i1;
            var root = new DoublyLinkedItem("foo", i1);
            i1.Previous = root;

            DeleteNodesFromDoublyLInkedList.Delete("foo", i2);

            int counter = 1;
            DoublyLinkedItem cUp = i2.Previous;
            DoublyLinkedItem cDown = i2.Next;

            while (cUp != null)
            {
                if (cUp.Value == "foo")
                {
                    Assert.Fail("Node with value 'foo' hasn't been removed");                    
                }
                cUp = cUp.Previous;
                
                counter++;
            }

            while (cDown != null)
            {
                if (cDown.Value == "foo")
                {
                    Assert.Fail("Node with value 'foo' hasn't bdeen removed");
                }
                cDown = cDown.Next;
                counter++;
            }
            Assert.AreEqual(3, counter);
        }

Solution:

    public class DeleteNodesFromDoublyLInkedList
    {
        public static void Delete(string value, DoublyLinkedItem node)
        {
            DoublyLinkedItem cUp = node;
            DoublyLinkedItem cDown = node;

            while (cUp != null)
            {
                if (cUp.Value == value)
                {
                    DeleteNode(cUp);
                }
                cUp = cUp.Previous;
            }

            while (cDown != null)
            {
                if (cDown.Value == value)
                {
                    DeleteNode(cDown);
                }
                cDown = cDown.Next;
            }
        }

        private static void DeleteNode(DoublyLinkedItem item)
        {
            bool root = item.Previous == null;
            if (root)
            {
                if (item.Next == null)
                {
                    return;
                }
                item.Next.Previous = null;
            }
            else
            {
                item.Previous.Next = item.Next;
            }
            
        }
    }

    public class DoublyLinkedItem
    {
        private readonly string value;

        public DoublyLinkedItem(string value, DoublyLinkedItem next)
        {
            this.value = value;
            Next = next;
        }

        public DoublyLinkedItem Next { get; set; }
        public DoublyLinkedItem Previous { get; set; }

        public string Value
        {
            get { return value; }
        }
    }