def test_remove_node(self):
"""
Tests removing a node from the graph.
"""
g = DAG()
g.add_node(1)
g.add_node(2)
g.add_node(3)
g.add_edge(1, 2)
g.add_edge(1, 3)
g.add_edge(2, 3)
g.remove_node(3)
self.assertNotIn(3, g.all_nodes)
self.assertEqual(len(g.dependent_nodes(1)), 1)
self.assertIn(2, g.dependent_nodes(1))
self.assertEqual(len(g.dependent_nodes(2)), 0)
g.remove_node(1)
self.assertEqual(g.in_degree[g.nodes_map[2].id], 0)
def test_add_edge(self):
"""
Tests adding edges to a DAG.
"""
g = DAG()
g.add_node(1)
g.add_node(2)
g.add_edge(1, 2)
self.assertEqual(len(g.dependent_nodes(1)), 1)
self.assertIn(2, g.dependent_nodes(1))
# In-degrees updated
self.assertEqual(g.in_degree[g.nodes_map[1].id], 0)
self.assertEqual(g.in_degree[g.nodes_map[2].id], 1)
g.add_node(3)
g.add_edge(1, 3)
self.assertEqual(len(g.dependent_nodes(1)), 2)
self.assertIn(3, g.dependent_nodes(1))
# In-degrees updated
self.assertEqual(g.in_degree[g.nodes_map[1].id], 0)
self.assertEqual(g.in_degree[g.nodes_map[3].id], 1)
g.add_edge(2, 3)
self.assertEqual(len(g.dependent_nodes(2)), 1)
self.assertIn(3, g.dependent_nodes(2))
# In-degrees updated
self.assertEqual(g.in_degree[g.nodes_map[3].id], 2)
# Add a same edge again - nothing changed?
g.add_edge(1, 3)
self.assertEqual(len(g.dependent_nodes(1)), 2)
# Add an edge resulting in a cycle
with self.assertRaises(InvalidDAGException):
g.add_edge(3, 1)
