In this work, a comprehensive functional-based test method is presented to integrate the test of Network-on-Chip interconnects and routers. Experimental results show that fault coverage can reach up to 100% of interconnect faults and over 90% of router faults. The test structures needed to implement the test method are presented and the scalability of the method is discussed. We show that our approach scales well with the number of routers and channel width. The cost of the functional test strategy and the cost of a scan-based strategy are also analyzed in order to present scenarios where each strategy fits better.