public void Enumerate_ConcreteType()
{
SinglyLinkedListKeyNode <int, int> list = null;
list = list.Add(0, 1);
list = list.Add(1, 2);
list = list.Add(2, 3);
int[] results = list.ToArray();
Assert.Equal(3, results.Length);
Assert.Equal(3, results[0]);
Assert.Equal(2, results[1]);
Assert.Equal(1, results[2]);
}
