@Override
    public Device getDevice(DeviceId deviceId) {
        return devices.get(deviceId);
    }
@Test
    public final void testGetDevice() {

        putDevice(DID1, SW1);

        assertDevice(DID1, SW1, deviceStore.getDevice(DID1));
        assertNull("DID2 shouldn't be there", deviceStore.getDevice(DID2));
    }