Like all other Gyms in Paldea, the Alfornada Gym building itself is simply used for registering Gym challengers. The Gym Test and Gym battle are both conducted outside the building, within Alfornada.
The Alfornada Gym Test has the player complete the Emotional Spectrum Practice, an exercise regimen created by Tulip. This is accomplished by copying Dendra's instructions and pressing a button that causes the player and their lead Pokémon to assume the correct kind of expression. The regimen has two halves, each of which is followed by a battle against a Gym Trainer.