def test_no_limits_with_negative(self):
"""Test that we're not enforcing a trial limit if set to negative."""
backend = FakeYorktown()
qc = QuantumCircuit(3)
qc.h(0)
cmap = CouplingMap(backend.configuration().coupling_map)
implicit_max = len(cmap.graph.edge_list()) + 15
properties = backend.properties()
# Run without any limits set
vf2_pass = VF2Layout(cmap,
properties=properties,
seed=42,
max_trials=0)
property_set = {}
with self.assertLogs("qiskit.transpiler.passes.layout.vf2_layout",
level="DEBUG") as cm:
vf2_pass(qc, property_set)
for output in cm.output:
self.assertNotIn("is >= configured max trials", output)
last_line = cm.output[-1]
# The last line should be
# DEBUG:qiskit.transpiler.passes.layout.vf2_layout: Trial n has score 0.122
trials = int(last_line.split(" ")[1])
self.assertGreater(trials, implicit_max)
self.assertEqual(set(property_set["layout"].get_physical_bits()),
{3, 1, 0})
def test_time_limit_exceeded(self):
"""Test the pass stops after time_limit is reached."""
backend = FakeYorktown()
qr = QuantumRegister(2)
qc = QuantumCircuit(qr)
qc.x(qr)
qc.measure_all()
cmap = CouplingMap(backend.configuration().coupling_map)
properties = backend.properties()
vf2_pass = VF2Layout(cmap,
properties=properties,
seed=-1,
time_limit=0.0)
property_set = {}
with self.assertLogs("qiskit.transpiler.passes.layout.vf2_layout",
level="DEBUG") as cm:
vf2_pass(qc, property_set)
for output in cm.output:
if output.startswith(
"DEBUG:qiskit.transpiler.passes.layout.vf2_layout:VF2Layout has taken"
) and output.endswith("which exceeds configured max time: 0.0"):
break
else:
self.fail("No failure debug log message found")
self.assertEqual(set(property_set["layout"].get_physical_bits()),
{2, 0})
def test_with_properties(self):
"""Test scores with properties."""
backend = FakeYorktown()
cmap = CouplingMap(backend.configuration().coupling_map)
properties = backend.properties()
vf2_pass = VF2Layout(cmap, properties=properties)
qr = QuantumRegister(2)
layout = Layout({qr[0]: 4, qr[1]: 2})
bad_score = vf2_pass._score_layout(layout)
self.assertAlmostEqual(0.4075, bad_score)
better_layout = Layout({qr[0]: 1, qr[1]: 3})
better_score = vf2_pass._score_layout(better_layout)
self.assertAlmostEqual(0.0588, better_score)
def test_with_properties(self):
"""Test it finds the least noise perfect layout with no properties."""
backend = FakeYorktown()
qr = QuantumRegister(2)
qc = QuantumCircuit(qr)
qc.x(qr)
qc.measure_all()
cmap = CouplingMap(backend.configuration().coupling_map)
properties = backend.properties()
vf2_pass = VF2Layout(cmap, properties=properties)
property_set = {}
vf2_pass(qc, property_set)
self.assertEqual(set(property_set["layout"].get_physical_bits()),
{1, 3})
def test_max_trials_exceeded(self):
"""Test it exits when max_trials is reached."""
backend = FakeYorktown()
qr = QuantumRegister(2)
qc = QuantumCircuit(qr)
qc.x(qr)
qc.measure_all()
cmap = CouplingMap(backend.configuration().coupling_map)
properties = backend.properties()
vf2_pass = VF2Layout(cmap,
properties=properties,
seed=-1,
max_trials=1)
property_set = {}
with self.assertLogs("qiskit.transpiler.passes.layout.vf2_layout",
level="DEBUG") as cm:
vf2_pass(qc, property_set)
self.assertIn(
"DEBUG:qiskit.transpiler.passes.layout.vf2_layout:Trial 1 is >= configured max trials 1",
cm.output,
)
self.assertEqual(set(property_set["layout"].get_physical_bits()),
{2, 0})