It can't already be confirmed if the labtest is not completed yet. It sounds like you still misunderstood the nurse.
They're doing a labtest for Coronavirus because she's been in contact with a nurse who's been in contact with a Coronavirus patient. It is just standard protocol to get tested in that case.
I asked her again, now it's confirmed it's Coronavirus. It takes time to get lab test, they can't confirm it immediately it seems for now.