def test_ancestors(self):
graph = Graph()
graph.add_edges([
Edge('a', 'b', 1),
Edge('a', 'c', 1),
Edge('c', 'd', 1)])
self.assertCountEqual(graph.ancestors('a'), ['a'])
self.assertCountEqual(graph.ancestors('b'), ['a', 'b'])
self.assertCountEqual(graph.ancestors('c'), ['a', 'c'])
self.assertCountEqual(graph.ancestors('d'), ['a', 'c', 'd'])
def test_ancestors_with_crossing_paths(self):
graph = Graph()
graph.add_edges([
Edge('a', 'b', 1),
Edge('a', 'c', 1),
Edge('c', 'd', 1),
Edge('b', 'd', 1)])
self.assertCountEqual(graph.ancestors('d'), ['a', 'b', 'c', 'd'])