Are you customizing anything in OOB FSM module? I don't think it's worth testing OOB FSM capability as it is a COTS product. Depending on your organization's business case, there may be a need to customize the table schema (e.g., adding new fields), or trigger a custom flow from the flow designer or even having a specific catalog item/record producer to fulfill a specific use case, which would be an ideal candidate for testing.
You can develop your test cases based on your business and technical requirements.
If that answers your questions, please mark it as complete.
