def test_delete_top_one_element_list(self):
     linked = LinkedList(['two'])
     linked.delete_from_top()
     self.assertEqual(None, linked.first_node)
 def test_delete_top_two_element_list(self):
     linked = LinkedList(['one', 'two'])
     linked.delete_from_top()
     self.assertEqual('two', linked.first_node.data)
     self.assertEqual(None, linked.first_node.next)
 def test_delete_top_empty_list(self):
     linked = LinkedList([])
     with self.assertRaises(IndexError):
         linked.delete_from_top()