Yes, we have aligned test data across most relevant APIs and introduced a process to ensure test data for future APIs is aligned where appropriate.
For sandbox testing, details are generally given within the endpoint documentation for each API - for example, see Personal Demographics Service - FHIR API - NHS Digital.
For integration testing, details of the test data are supplied in the “Environments and testing” section of the relevant APIs - for example, see Personal Demographics Service - FHIR API - NHS Digital.