Do something that is actually the type of work. If you need legacy code support, refactor some legacy code (it doesn't have to be YOUR code). If you need a vibe code product manager, do some vibe coding & project management for a sufficiently interesting use case. If you need a QA Engineer, give them a bug to solve & ask them to write a bug report.

Testing the skills people will use is less obvious than I realized. I could have communicated "do the work" more effectively as "test the actual skills people will use".