def test_evaluate_node_fractional(self):
bb = BranchAndBound(small_branch,
Node=PCBDFSNode,
pseudo_costs={},
strong_branch_iters=5)
bb._evaluate_node(bb.root_node)
# check attributes
self.assertFalse(bb._best_solution, 'best solution should not change')
self.assertTrue(bb.global_upper_bound == float('inf'),
'shouldnt change')
self.assertTrue(bb.global_lower_bound > -float('inf'), 'should change')
self.assertTrue(bb._node_queue.qsize() == 2,
'should branch and add two nodes')
self.assertTrue(bb._kwargs['pseudo_costs'], 'something should be set')
self.assertTrue(bb._kwargs['strong_branch_iters'],
'something should be set')
self.assertTrue(bb.evaluated_nodes == 1,
'only one node should be evaluated')
# check function calls - recycle object since it has attrs already set
with patch.object(bb, '_process_rtn') as pr, \
patch.object(bb, '_process_branch_rtn') as pbr, \
patch.object(bb.root_node, 'bound') as bd, \
patch.object(bb.root_node, 'branch') as bh:
bb._evaluate_node(bb.root_node)
self.assertTrue(pr.call_count == 1) # direct calls
self.assertTrue(pbr.call_count == 1)
self.assertTrue(0 == pbr.call_args.args[0],
'root node id should be first call arg')
self.assertTrue(bd.call_count == 1)
self.assertTrue(bh.call_count == 1)
def test_evaluate_node_infeasible(self):
bb = BranchAndBound(infeasible)
bb._evaluate_node(bb.root_node)
# check attributes
self.assertTrue(bb._node_queue.empty(),
'inf model should create no nodes')
self.assertFalse(bb._best_solution, 'best solution should not change')
self.assertTrue(bb.global_upper_bound == float('inf'),
'shouldnt change')
self.assertTrue(bb.global_lower_bound == float('inf'),
'shouldnt change')
self.assertTrue(bb.evaluated_nodes == 1,
'only one node should be evaluated')
# check function calls - recycle object since it has attrs already set
with patch.object(bb, '_process_rtn') as pr, \
patch.object(bb, '_process_branch_rtn') as pbr, \
patch.object(bb.root_node, 'bound') as bd, \
patch.object(bb.root_node, 'branch') as bh:
bb._evaluate_node(bb.root_node)
self.assertTrue(pr.call_count == 1)
self.assertTrue(pbr.call_count == 0)
self.assertTrue(bd.call_count == 1)
self.assertTrue(bh.call_count == 0)
def test_evaluate_node_unbounded(self):
bb = BranchAndBound(unbounded)
bb._evaluate_node(bb.root_node)
# check attributes
self.assertTrue(bb._unbounded)
self.assertTrue(bb.evaluated_nodes == 1,
'only one node should be evaluated')
def test_evaluate_node_properly_prunes(self):
bb = BranchAndBound(no_branch)
bb._global_upper_bound = -2
called_node = BaseNode(bb.model.lp, bb.model.integerIndices, -4)
pruned_node = BaseNode(bb.model.lp, bb.model.integerIndices, 0)
with patch.object(called_node, 'bound') as cnb, \
patch.object(pruned_node, 'bound') as pnb:
cnb.return_value = {}
pnb.return_value = {}
bb._node_queue.put(called_node)
bb._node_queue.put(pruned_node)
bb._evaluate_node(bb._node_queue.get())
bb._evaluate_node(bb._node_queue.get())
self.assertTrue(cnb.call_count == 1, 'first node should run')
self.assertFalse(pnb.call_count, 'second node should get pruned')
self.assertTrue(bb._node_queue.empty())
def test_evaluate_node_integer(self):
bb = BranchAndBound(no_branch)
bb._evaluate_node(bb._root_node)
# check attributes
self.assertTrue(all(bb._best_solution == [1, 1, 0]))
self.assertTrue(bb._global_upper_bound == -2)
self.assertTrue(bb._node_queue.empty(),
'immediately optimal model should create no nodes')
# check function calls - recycle object since it has attrs already set
with patch.object(bb, '_process_rtn') as pr, \
patch.object(bb, '_process_branch_rtn') as pbr, \
patch.object(bb._root_node, 'bound') as bd, \
patch.object(bb._root_node, 'branch') as bh:
bb._evaluate_node(bb._root_node)
self.assertTrue(pr.call_count == 1)
self.assertTrue(pbr.call_count == 0)
self.assertTrue(bd.call_count == 1)
self.assertTrue(bh.call_count == 0)
def test_evaluate_node_fractional(self):
bb = BranchAndBound(small_branch, Node=PCBDFSNode)
bb._evaluate_node(bb._root_node)
# check attributes
self.assertFalse(bb._best_solution, 'best solution should not change')
self.assertTrue(bb._global_upper_bound == float('inf'),
'shouldnt change')
self.assertTrue(bb._node_queue.qsize() == 2,
'should branch and add two nodes')
self.assertTrue(bb._pseudo_costs, 'something should be set')
# check function calls - recycle object since it has attrs already set
with patch.object(bb, '_process_rtn') as pr, \
patch.object(bb, '_process_branch_rtn') as pbr, \
patch.object(bb._root_node, 'bound') as bd, \
patch.object(bb._root_node, 'branch') as bh:
bb._evaluate_node(bb._root_node)
self.assertTrue(pr.call_count == 1) # direct calls
self.assertTrue(pbr.call_count == 1)
self.assertTrue(bd.call_count == 1)
self.assertTrue(bh.call_count == 1)
def test_evaluate_node_unbounded(self):
bb = BranchAndBound(unbounded)
bb._evaluate_node(bb._root_node)
# check attributes
self.assertTrue(bb._unbounded)