Found chicken

Hello! I recently found a chicken that was abandoned on the side of the road near my house. She was in a pet carrier with a small bowl of water and some bird seed. I brought her home and have her in quarantine now. I plan on keeping her separate from my current flock for 2 weeks and am monitoring her for signs of illness. Currently she seems perfectly healthy. I looked into tests that check for respiratory diseases and the forever diseases but found them to be a little pricey. Any recommendations on what tests I should run or where to get the tests cheapest would be appreciated. Im not sure what breed she is or her age. Im a little suspicious why someone would leave her on the side of the road in 95° weather.