Sure it is. It makes all kinds of testable predictions, which have been confirmed. One good example is the evolution of antibiotic-resistant bacteria, which IIRC was predicted by (among others) Alexander Fleming, who discovered penicillin. If more people had listened to that prediction of evolutionary theory (which was obvious even when it was made and is even more obvious today, when we can sequence bacterial DNA and see it changing in response to selection pressures imposed by the use of different antibiotics), we would not have the major problem with resistant bacteria that we have today.