public void disconnectWithException(BleException exception) {
        if (connectionSubject != null) {
            connectionSubject.onError(exception);
        }
    }
Set a BLE connection mock. Calling this method is required.
mockrxandroidble/src/main/java/com/polidea/rxandroidble2/mockrxandroidble/RxBleDeviceMock.java