I had to renew an instrument rating in a model of chopper (glass screens, FADEC) that was unique in the country. The CA$A testing officer had a bare endorsement on a different model (steam gauges, no FADEC) from 10 years previously, but CA$A considered him competent to conduct the test.
Before starting up, I TOLD him that he was not to touch any engine controls, and if he wanted to give me an engine failure, he was to just say "Engine failure number 2" and I would look after the throttle.
At the end of the successful test, he begged me to be allowed to fly it back to home base, just to have a feel of the aircraft.