This situation is a good CRM exercise – knowledge, situation assessment, decision making, and action; manage the surprise of the situation which might not be detected until the cabin alt warning goes.
AFAIR the acceptable leak rate for an air-test was ~2000ft/min.
My last type required a descent for a relight, thus commence aircraft descent at 1000ft/min (FL300-250) – 5min, but cabin rising from 8000ft towards ambient at 2000ft/min – 3 min before 14000ft pax O2 action required. However, as the aircraft descends the change in pressure differential may reduce the leak rate, and there might be an opportunity for the APU to supply air.
Crew O2 early – less you forget. If time, consider why both engines should go out at the same time (if only to discuss with the instructor during debrief as to what he considers relevant to creating the situation).