public void AddFirst_CheckHead_CheckTail_CheckCount()
{
// Act
linkedList.AddNodeInFirst(5);
linkedList.AddNodeInFirst(4);
linkedList.AddNodeInFirst(3);
// Assert
Assert.Equal(tailExpected, linkedList.Tail);
Assert.Equal(headExpected, linkedList.Head);
Assert.Equal(middleExpected, linkedList.Head.Next);
Assert.Equal(middleExpected, linkedList.Tail.Previous);
Assert.Equal(3, linkedList.Count);
}