Well it would depend....
If I was under ATC, I'd expect the controller to give avoiding action, but if he/she was indecisive, I'd keep a very sharp lookout and be prepared to see and avoid, including configuring the a/c for a quick evasion.
If it was an A/g or AFISO tower service I would be keeping a sharp look out and be prepared to make a sharp left or right accordingly.
Most likely the traffic is above the circuit, but there is no room for complacency.
I've had an aircraft climb up the glideslope towards me on a 2 mile final under ATC, who were not aware of it's presence! We saw it at about 3/4 mile and took avoiding action.