def test_topsort_string_nodes(self):
"""
Tests the toplogical sort when strings are used for node objects.
"""
g = DAG()
nodes = ['shirt', 'pants', 'tie', 'belt', 'shoes', 'socks', 'pants']
for node in nodes:
g.add_node(node)
edges = (
('shirt', 'tie'),
('shirt', 'belt'),
('belt', 'tie'),
('pants', 'tie'),
('pants', 'belt'),
('pants', 'shoes'),
('pants', 'shirt'),
('socks', 'shoes'),
('socks', 'pants'),
)
for edge in edges:
g.add_edge(*edge)
topsort = list(g.topsort_nodes())
for node in nodes:
self.assertIn(node, topsort)
for node1, node2 in edges:
self.assertTrue(topsort.index(node2) > topsort.index(node1))
def test_topsort_simple(self):
"""
Tests the topological sort of the DAG class.
"""
g = DAG()
g.add_node(1)
g.add_node(2)
g.add_node(3)
g.add_edge(1, 2)
g.add_edge(2, 3)
topsort = list(g.topsort_nodes())
self.assertSequenceEqual([1, 2, 3], topsort)
def test_topsort_no_dependencies(self):
"""
Tests the toplogical sort of the DAG class when the given DAG has no
dependencies between the nodes.
"""
g = DAG()
g.add_node(1)
g.add_node(2)
g.add_node(3)
topsort = list(g.topsort_nodes())
nodes = [1, 2, 3]
# The order in this case cannot be mandated, only that all the nodes
# are in the output
for node in nodes:
self.assertIn(node, topsort)
def test_topsort_complex(self):
"""
Tests the toplogical sort when a more complex graph is given.
"""
g = DAG()
nodes = list(range(13))
for node in nodes:
g.add_node(node)
edges = (
(0, 1),
(0, 2),
(0, 3),
(0, 5),
(0, 6),
(2, 3),
(3, 4),
(3, 5),
(4, 9),
(6, 4),
(6, 9),
(7, 6),
(8, 7),
(9, 10),
(9, 11),
(9, 12),
(11, 12),
)
for edge in edges:
g.add_edge(*edge)
topsort = list(g.topsort_nodes())
# Make sure all nodes are found in the toplogical sort
for node in nodes:
self.assertIn(node, topsort)
# Make sure that all dependent nodes are found after the nodes they
# depend on.
# Invariant: for each edge (n1, n2) position(n2) in the topological
# sort must be strictly greater than the position(n1).
for node1, node2 in edges:
self.assertTrue(topsort.index(node2) > topsort.index(node1))
