Simple way to test on real device without the need to use serial id

There should be a way to simply test on device, without the need to use serial id, if only one device is connected. Adb has this functionality (if only one device (real or emulated) is connected, it uses it, or with -d switch to use real device (-e for emulated one)). Droidium should also allow this and quit with error if no serial id is specified, but more devices are connected.