The development of wireless sensor networks deals with several difficulties, including time, cost and complexity of testing. In particular, indoor environment poses several specific constraints on radio wave propagation due to density of obstacles. This must be taken into account if we want to discover and validate network configurations and communication paths. We suggest the use of virtual worlds, exploiting their inherent features for modeling of 3D environment, to simulate wireless sensor networks in order to deal with this problem. We have created an initial version of one such tool, which supports discovery and testing of configurations and communication paths within indoor wireless sensor networks. The validity of our approach was confirmed through experiments performed in this tool, in parallel with real-world experiments in a similar setting.