def test_can_add_multiple_edges_between_two_vertices(self):
graph = UndirectedGraph()
graph.add_edge(0, 1, 1)
graph.add_edge(0, 1, 2)
adjacency_list = graph.get_adjacency_list()
self.assertEqual(2, len(adjacency_list))
self.assertEqual(2, len(adjacency_list[0]))
self.assertListEqual([0, 0],
sorted(map(lambda e: e.start, adjacency_list[0])))
self.assertListEqual([1, 1],
sorted(map(lambda e: e.end, adjacency_list[0])))
self.assertListEqual([1, 2],
sorted(map(lambda e: e.weight,
adjacency_list[0])))
self.assertEqual(2, len(adjacency_list[1]))
self.assertListEqual([1, 1],
sorted(map(lambda e: e.start, adjacency_list[1])))
self.assertListEqual([0, 0],
sorted(map(lambda e: e.end, adjacency_list[1])))
self.assertListEqual([1, 2],
sorted(map(lambda e: e.weight,
adjacency_list[1])))
edges = graph.get_edges()
self.assertEqual(4, len(edges))
self.assertListEqual([0, 0, 1, 1], sorted(map(lambda e: e.start,
edges)))
self.assertListEqual([0, 0, 1, 1], sorted(map(lambda e: e.end, edges)))
self.assertListEqual([1, 1, 2, 2],
sorted(map(lambda e: e.weight, edges)))
def test_returns_minimum_edge_when_has_two_edges_with_different_weight(
self):
graph = UndirectedGraph()
graph.add_edge(0, 1, 1)
graph.add_edge(0, 1, 2)
mst = minimum_spanning_tree(graph.get_adjacency_list())
self.__compare_vertices([0, 1], mst.get_adjacency_list())
self.__compare_edges([Edge(0, 1, 1), Edge(1, 0, 1)], mst.get_edges())
def test_returns_two_edges_for_two_edges_starting_in_same_vertex(self):
graph = UndirectedGraph()
graph.add_edge(0, 1, 1)
graph.add_edge(0, 2, 2)
mst = minimum_spanning_tree(graph.get_adjacency_list())
self.__compare_vertices([0, 1, 2], mst.get_adjacency_list())
self.__compare_edges(
[Edge(0, 1, 1),
Edge(1, 0, 1),
Edge(0, 2, 2),
Edge(2, 0, 2)], mst.get_edges())
def test_returns_mst_for_graph_with_loops(self):
graph = UndirectedGraph()
graph.add_edge('A', 'B', 3)
graph.add_edge('A', 'C', 4)
graph.add_edge('D', 'B', 6)
graph.add_edge('E', 'B', 2)
graph.add_edge('B', 'C', 5)
graph.add_edge('C', 'E', 7)
mst = minimum_spanning_tree(graph.get_adjacency_list())
self.__compare_vertices(['A', 'B', 'C', 'D', 'E'],
mst.get_adjacency_list())
self.__compare_edges([
Edge('A', 'B', 3),
Edge('B', 'A', 3),
Edge('B', 'E', 2),
Edge('E', 'B', 2),
Edge('A', 'C', 4),
Edge('C', 'A', 4),
Edge('B', 'D', 6),
Edge('D', 'B', 6)
], mst.get_edges())
def test_does_not_change_tree(self):
graph = UndirectedGraph()
graph.add_edge(0, 1, 1)
graph.add_edge(0, 6, 1)
graph.add_edge(2, 3, 2)
graph.add_edge(2, 4, 3)
graph.add_edge(4, 5, 4)
mst = minimum_spanning_tree(graph.get_adjacency_list())
self.__compare_vertices([0, 1, 2, 3, 4, 5, 6],
mst.get_adjacency_list())
self.__compare_edges([
Edge(0, 1, 1),
Edge(1, 0, 1),
Edge(0, 6, 1),
Edge(6, 0, 1),
Edge(2, 3, 2),
Edge(3, 2, 2),
Edge(2, 4, 3),
Edge(4, 2, 3),
Edge(4, 5, 4),
Edge(5, 4, 4)
], mst.get_edges())
def test_adding_single_edge_produces_two_directed_edges(self):
graph = UndirectedGraph()
graph.add_edge(0, 1, 1)
adjacency_list = graph.get_adjacency_list()
self.assertEqual(2, len(adjacency_list))
self.assertEqual(1, len(adjacency_list[0]))
self.assertEqual(0, adjacency_list[0][0].start)
self.assertEqual(1, adjacency_list[0][0].end)
self.assertEqual(1, adjacency_list[0][0].weight)
self.assertEqual(1, len(adjacency_list[1]))
self.assertEqual(1, adjacency_list[1][0].start)
self.assertEqual(0, adjacency_list[1][0].end)
self.assertEqual(1, adjacency_list[1][0].weight)
edges = graph.get_edges()
self.assertEqual(2, len(edges))
self.assertListEqual([0, 1], sorted(map(lambda e: e.start, edges)))
self.assertListEqual([0, 1], sorted(map(lambda e: e.end, edges)))
self.assertListEqual([1, 1], sorted(map(lambda e: e.weight, edges)))
def test_returns_single_edge_for_single_edge_in_graph(self):
graph = UndirectedGraph()
graph.add_edge(0, 1, 1)
mst = minimum_spanning_tree(graph.get_adjacency_list())
self.__compare_vertices([0, 1], mst.get_adjacency_list())
self.__compare_edges([Edge(0, 1, 1), Edge(1, 0, 1)], mst.get_edges())
def test_graph_is_empty_by_default(self):
graph = UndirectedGraph()
self.assertEqual(0, len(graph.get_adjacency_list()))
self.assertEqual(0, len(graph.get_edges()))
