Hi
I have not heard of, or seen any sexually transmitted infections (STI) pass when dry humping, it is probably one of the safest ways to have sex.
Given this there would be no need to test for this event. Since most STI do not show symptoms we recommend that people get tested every 3-6 months if they have had any type of activity that could pass a STI.
Let us know if you have any more questions or concerns.
Health Nurse