Trust and reputation models research and development for distributed systems such as P2P networks, wireless sensor networks (WSNs) or multi-agent systems has arisen and taken importance in the last recent years among the international research community. However it is not always easy to check the correctness and accuracy of a model and even more, to compare it against other trust and reputation models. This paper presents TRMSim-WSN, a Java-based trust and reputation models simulator aimed to provide an easy way to test a trust and/or reputation model over WSNs and to compare it against other models. It allows the user to adjust several parameters such as the percentage of malicious nodes or the possibility of forming a collusion, among many others.