def test_graph_toposort_visitor(self):
graph = Graph(range(6))
graph.add_edges(5, 2, 0)
graph.add_edges(4, 0, 1)
graph.add_edge(2, 3)
graph.add_edge(3, 1)
actual = GraphToposortVisitor.visit(graph)
expect = [5, 4, 2, 3, 1, 0]
self.assertEquals(actual, expect)
