def test_distance_error(self):
"""Test distance between unconected physical_qubits."""
graph = CouplingMap()
graph.add_physical_qubit(0)
graph.add_physical_qubit(1)
self.assertRaises(CouplingError, graph.distance, 0, 1)
def test_add_physical_qubits(self):
coupling = CouplingMap()
self.assertEqual("", str(coupling))
coupling.add_physical_qubit(0)
self.assertEqual([0], coupling.physical_qubits)
self.assertEqual("", str(coupling))
