There are several tests for olfactory ability.
The animal locates a hidden object (some food like cheese) by order, and latency to locate the hidden object is measured as the index of olfactory ability. Another test is to quantitated time spent sniffing an attractive, novel ordor, and cumulative time spent sniffing the odorant is quantitated by recording. More sophisticated test is odor discrimination in which the animals is required to choose between two ordors to obtain food reward.