def test_is_connected(self):
v = Vertex('v')
w = Vertex('w')
e1 = Arc(v, w)
e2 = Arc(w,v)
dg = DirectedGraph([v, w], [e1,e2])
self.assertEqual(dg.is_strongly_connected(),True)
dg.remove_edge(w,v)
self.assertEqual(dg.is_strongly_connected(),False)
def test_complete(self):
"""a two-vertex complete graph is strongly connected."""
v = Vertex('v')
w = Vertex('w')
dg = DirectedGraph([v,w])
dg.add_all_edges()
self.assertTrue(dg.is_strongly_connected())
