Whoa, evolution has been tested? If you can show where evolution was tested, I'll back down now.
Every year there are viruses and bacteria that develop resistances and immunities to the treatments and antibiotics that had worked only months or weeks before. Think about the fact that the entire planet is currently tooling up to fight a bird-flu pandemic, despite the fact that it can't currently transmit from human-to-human yet, only bird-to-bird and bird-to-human.
So what's the panic all about? The fear is that the flu virus will develop a strain that will eventually transmit from human-to-human and will be incredibly had to fight.
But, if it's not currently a danger except for those that live and work around birds, how will it happen that it might become a danger for the general population?
Well, by the same processes that Darwin proposed so many years ago: Natural selection and random mutation that leads to evolutionary advantage. It's happening every day, all around us, just at the micro scale. Bacteria and viruses multiply so fast that we can actually see those processes in action.
Unfortunately, life on the macro scale takes so long to reproduce that it's impossible for us to see in real-time, and have no evidence that's the way it happened except by looking into the past. But why should we expect that the processes that work on very small, quick-lived life-forms on our planet are any different that the processes that affect the larger, slower-lived life forms? Especially when the fossil record and DNA evidence seems to indicate that's exactly how it happened.