def test_remove_model_when_exists():
system = SimulatedSystem()
battery = SinglePhaseGenerator()
uuid = system.add_model(battery)
assert system.remove_model(uuid)
assert len(system.devices) == 0
assert len(system.subscriptions) == 0
def test_remove_model_when_no_devices():
system = SimulatedSystem()
assert system.remove_model(uuid.uuid1()) is False