def test_edges(self):
g = Graph()
v1, v2, v3 = g.add_vertices(3)
g.add_edge((v1, v2))
self.assertEqual(g.num_edges(), 1)
self.assertTrue(g.connected(v1, v2))
self.assertTrue(v2 in g.neighbours(v1))
self.assertEqual(g.vertex_degree(v1), 1)
self.assertFalse(g.connected(v1, v3))
e = g.edge(v1, v2)
self.assertEqual(g.edge_type(e), 1)
g.set_edge_type(e, 2)
self.assertEqual(g.edge_type(e), 2)
g.remove_edge(e)
self.assertEqual(g.num_edges(), 0)
self.assertFalse(g.connected(v1, v2))
def test_copy(self):
g = Graph()
v1, v2 = g.add_vertices(2)
g.add_edge((v1, v2), 2)
g2 = g.copy()
self.assertEqual(g.num_vertices(), g2.num_vertices())
self.assertEqual(g.num_edges(), g2.num_edges())
v1, v2 = list(g2.vertices())
self.assertEqual(g.edge_type(g.edge(v1, v2)), 2)
def test_empty_graph(self):
g = Graph()
self.assertEqual(g.num_vertices(), 0)
self.assertEqual(g.num_edges(), 0)
