Sharing my experiences.
Lung capacity test
They ask you to blow into a machine as hard as you can, then inhale. Need to pass a certain level based on your height, weight and sex.
Mask seal test
They teach you to wear and take off the mask. After you put the mask on, they put a hood on you (a bit like those clean room hoods) and spray something to test the mask. I think it's a powder. If you taste (not smell) anything, the mask leaks. In the hood, they ask you to turn/tilt your head and bend down.