LEM Don’t think up things to do as they might be hazardous, talk to the manufacturer first. A reputable manufacturer will show you the production (or return to service) flight test results for that aircraft, or if not applicable, provide a general schedule for your guidance. In addition to choosing specific tests it is most important to have an understanding of how and where the test should be conducted.
My recommendation would be to fly the aircraft and operate the systems normally, if there is anything grossly wrong it will show up. If the flight is in conjunction with the manufacturer then use the flight time to enhance your knowledge of the aircraft and handling – perhaps exploring the boundaries of normal / non normal flight in a controlled environment – much better than the simulator.