MD500D Check Airmen reported ATC failure to separate MD500 from departure traffic that overflew them from a converging runway resulting in a rejected takeoff.

Narrative

During the conduct of a check ride; myself and the applicant were in a right hand traffic pattern on runway XX of ZZZ. We had been 'Cleared for the option; runway XX'. After landing and beginning our takeoff roll to start another right hand pattern; we looked up and saw a plane directly in front of us flying the opposite direction about 300 ft above our runway. We realized this plane had just taken off from the converging runway; Runway XY; and was departing on a right-hand downwind departure. We slowed down; and aborted our takeoff/climb until the plane had passed. I made a call on the radio that 'We have the plane above us in sight'. The tower did not respond. We rejoined the traffic pattern without incident.Had we continued on a normal takeoff profile; we would have collided with the plane.I normally don't fly out of this airport. When discussing this with a local pilot; he said: 'Welcome to ZZZ'.This seems to highlight a serious safety gap in the control tower SOPs. Had the tower controller been paying attention; they would have held us on the runway until the departing plane was clear instead of letting this situation develop.