@Test public void shouldRemoveHead() {

  ListNode<Integer> head = new ListNode<Integer>(0);
  ListNode<Integer> n1 = new ListNode<Integer>(1);
  ListNode<Integer> n2 = new ListNode<Integer>(2);
  head.setNext(n1);
  n1.setNext(n2);
  deleteNode.delete(head);
  assertListContainsElements(new Integer[] { 1, 2 }, n1);
}