What are the approximations of open circuit and short circuit tests?

Firstly turn of the power before this test...
Using a resistance or continuity tester you should get the following results:

Short circuit: Very low resistance (nearly 0 ohms) or the bell will ring.
Open circuit: Very high resistance (Somewhere in the range of Mega ohms) or the bell will not ring.

The reason for this is because and open circuit has a gap in it (which has high resistance).
The short circuit has wires that are crossed and so has a really low resistance.