Testing File System Semantic Parity

Aspects of the subject matter described herein relate to testing filters for semantic parity. In aspects, a parity filter receives a request directed to a base file system. In response, the parity filter creates a semantically similar request to send to a tested file system. The parity filter then sends the requests to drivers associated with the file systems and receives responses thereto. The parity filter then compares the responses to determine if they are semantically equivalent. If they are different, the parity filter writes a log entry to a log. The parity filter may also directly or indirectly compare the two file systems associated with the drivers for semantic equivalency.