def test_numbers_of_self_loop(self):
graph = UndirectedGraph(4)
graph.add_edge(2, 2)
graph.add_edge(3, 3)
self.assertEqual(graph.numbers_of_self_loop(), 2)
graph = DirectedGraph(4)
graph.add_edge(2, 2)
graph.add_edge(3, 3)
self.assertEqual(graph.numbers_of_self_loop(), 2)
