Methods, systems, and apparatuses are provided to emulate bus transactions for a device under test (DUT). Test data is sent from a testing device to a cache of a DUT. When data needs to be read or written to locations outside of the cache (e.g., bus action is needed), a pseudo bus agent (PBA) is activated. The PBA emulates the reads or writes and provides pseudo data back to the cache. In some embodiments, results of bus transactions are compressed to form a bus signature that is provided back to the testing device for validation.