@Override
    public int getDeviceCount() {
        return devices.size();
    }
@Test
    public final void testGetDeviceCount() {
        assertEquals("initialy empty", 0, deviceStore.getDeviceCount());

        putDevice(DID1, SW1);
        putDevice(DID2, SW2);
        putDevice(DID1, SW1);

        assertEquals("expect 2 uniq devices", 2, deviceStore.getDeviceCount());
    }