def test_get_vertex(self):
g = Graph()
vertex = g.add_vertex('v1')
self.assertEqual(vertex, g.get_vertex('v1'))
self.assertEqual(vertex, g.get_vertex(vertex))
self.assertRaises(ValueError, g.get_vertex, 'v2')
def test_add_edge(self):
g = Graph()
g.add_vertex('v1')
g.add_vertex('v2')
g.add_vertex('v3')
g.add_vertex('v4')
edge = g.add_edge('v1', 'v2')
self.assertEqual(1, len(g.edges))
self.assertEqual(1, len(g.get_vertex('v1').neighbors))
self.assertEqual(1, len(g.get_vertex('v2').neighbors))
self.assertTrue(g.get_vertex('v1') in edge.get_vertices())
self.assertTrue(g.get_vertex('v2') in edge.get_vertices())
edge = g.add_edge('v3', 'v4', label='foo', value=10)
self.assertEqual('foo', edge.label)
self.assertEqual(10, edge.value)
