This is the trouble with carrying out checks where the examiner is acting as the copilot. I can sympathise with the examiner here because you really should know when to turn during the SID and if he behaves as an exemplary copilot he would talk you out of making any mistakes even though you might not really be competent ( I don't mean you personally).
The only answer is to conduct the check under realistic conditions, ie with a real copilot. Really the only way to do this is in a simulator.