Hermione stepped forward, refusing to think about how dark it was. "Hello?" she called. "I know someone's in here. I'm here to take the test."
There was a long silence, which she was sure was the most unnerving response possible. Then, from somewhere much further inside the cave - too far ahead to be contained within the small hill she'd seen from outside - came a sudden blaze of light.
Somebody was silhouetted in it.
"Hello?" Mentally, Hermione chided herself; there was no need to sound uncertain. Of course this is unnatural. You've been doing magic since you were eleven years old, and all of a sudden "unnatural" concerns you? She shook her head and kept walking, moving toward the shadow. "Hello, who's there?"
From this angle, she could see that the silhouette was definitely a female shape, and when it spoke, its voice was warm and affectionate and very feminine. "I am the test," she said softly, and then she stretched out a hand toward Hermione.
"Come closer so we can see each other, Hermione Granger. Come into the light."