I don’t. I suppose it is on the honor system
As long as it is on the honor system, don’t do anything other than get a supply of swabs you are more comfortable with just in case they abandon the honor system.
Then just say that you tested and that you tested negative.
We are dealing with dishonorable people with this whole plandemic. The honorable thing for you to do is to not do anything that can cause you unnecessary harm.