Evolution is tested every day in the laboratory, and it's tested every day in the field. There is not a single scientific theory that has been more controversial than evolution, and when theories are controversial, people devise tests to see if they're right. Evolution has been tested continuously for almost 150 years and not a single observation, not a single experimental result, has ever emerged in 150 years that contradicts the general outlines of the theory of evolution.
Any theory that can stand up to 150 years of continuous testing is a pretty darn good theory. We use evolution to develop drugs. We use evolution to develop vaccines. We use evolution to manage wildlife. We use evolution to interpret our own genome. Every one of these uses of evolution is a test, because if the use turns out to be inadequate, we would then go back and question the very idea of evolution itself. But evolution has turned out to be such a powerful, productive, and hardworking theory that it's survived that test of time.
an explanation for the observed changes in life through Earth history that has been tested numerous times and repeatedly confirmed. Evolution is an elegant theory that explains the history of life through geologic time; the diversity of living organisms, including their genetic, molecular, and physical similarities and differences; and the geographic distribution of organisms.