def test_should_find_simple_scc(self):
graph_with_cycle = {'foo': ['bar'],
'bar': ['foo']}
strongly_connected_components = tarjan_scc(graph_with_cycle)
self.assertEqual(strongly_connected_components, [('bar', 'foo')])
def test_should_only_find_single_item_components_when_there_are_no_cycles(self):
graph_with_no_cycles = {'foo': ['bar'],
'a': ['b'],
'baz': ['bar'],
'hello': ['foo']}
strongly_connected_components = tarjan_scc(graph_with_no_cycles)
self.assertEqual(strongly_connected_components, [
('b',), ('a',), ('bar',), ('foo',), ('baz',), ('hello',)])
def test_should_find_multi_item_components_when_there_are_cycles(self):
graph_with_cycle = {'foo': ['bar'],
'bar': ['baz'],
'baz': ['abc'],
'abc': ['foo'],
'f': ['g'],
'j': ['k']}
strongly_connected_components = tarjan_scc(graph_with_cycle)
self.assertEqual(strongly_connected_components, [
('baz', 'bar', 'foo', 'abc'), ('g',), ('f',), ('k',), ('j',)])
def test_should_not_find_any_scc_when_graph_empty(self):
empty_graph = {}
strongly_connected_components = tarjan_scc(empty_graph)
self.assertEqual(strongly_connected_components, [])
