In an embodiment, an SOC includes a global communication fabric that includes multiple independent networks having different communication and coherency protocols, and a plurality of input-output (I/O) clusters that includes different sets of local functional circuits. A given I/O cluster may be coupled to one or more of the independent networks and may include a particular set of local functional circuits, a local fabric coupled to the particular set of local functional circuits, and an interface circuit coupled to the local fabric and configured to bridge transactions between the particular set of local functional circuits and the global communication fabric. The interface circuit may include a programmable hardware transaction generator circuit configured to generate a set of test transactions that simulate interactions between the particular set of local functional circuits and a particular one of the one or more independent networks.