def setUp(self):
self.scc = StronglyConnectedComponents()
class TestStronglyConnectedComponents(unittest.TestCase):
def setUp(self):
self.scc = StronglyConnectedComponents()
def test_reverse_graph(self):
# input graph:
# 1-->2-->3
# ^ |
# | v
# 5<--6
graph = {
1: [2],
2: [3, 6],
6: [5],
5: [1],
3: [],
}
reversed_graph = self.scc.reverse_graph(graph)
# expected output graph:
# 1<--2<--3
# | ^
# v |
# 5-->6
expected_graph = {
1: [5],
2: [1],
6: [2],
5: [6],
3: [2],
}
for node in reversed_graph:
self.assertEqual(sorted(reversed_graph[node]), sorted(expected_graph[node]))
def test_dfs_updates_finishing_times(self):
# input graph:
# 1-->2-->3-->4
graph = {
1: [2],
2: [3],
3: [4],
4: [],
}
self.scc.dfs(graph, 1)
expected_order = [4, 3, 2, 1]
self.assertEqual(self.scc.finishing_order, expected_order)
def test_dfs_updates_components(self):
# input graph:
# 1-->2 3<--4
# ^ | | ^
# | v v |
# 5<--6 7-->8
graph = {
1: [2],
2: [6],
6: [5],
5: [1],
3: [7],
4: [3],
8: [4],
7: [8],
}
self.scc.source_node = 3
self.scc.dfs(graph, 3)
self.scc.source_node = 1
self.scc.dfs(graph, 1)
expected_components = {
3: [3, 4, 7, 8],
1: [1, 2, 5, 6],
}
for source_node in self.scc.components:
self.assertEqual(sorted(self.scc.components[source_node]),
sorted(expected_components[source_node]))
def test_strongly_connected_components(self):
# input graph:
# 1-->2-->3<--4
# ^ | | ^
# | v v |
# 5<--6 7-->8
graph = {
1: [2],
2: [3, 6],
6: [5],
5: [1],
3: [7],
4: [3],
8: [4],
7: [8],
}
res = self.scc.strongly_connected_components(graph)
for component in res:
component.sort()
assert [1, 2, 5, 6] in res
assert [3, 4, 7, 8] in res
