Due to lacking capability of simultaneously gathering information from the embedded system devices and networks, neither WSN simulators nor testbeds could explain how an abnormal exception in the embedded system would influence the network behaviors, and how the network congestion may possibly damage the health of the system on a single node. In this paper, to observe the WSN behavior from both network view and implementation view, we propose a new scheme which is able to improve the WSN testability. The proposed new approach is characterized with a network emulator based testbed, which provides a method of acquiring runtime information from embedded systems and from the visible and controllable environment connected with the real wireless sensor node devices but RF modules. A prototype of the proposed scheme has been implemented with XILINX FPGA and proved to be capable of providing the designers or researchers with more convenience in testing and debugging their application implementations on a more realistic and accurate platform.