Like most everything else they say, the IDer's assertion that evolution has never been tested is false. (At least the central idea of "selection of the fittest" has been both accidentally tested many times and tested in some controlled experiments.)
As example of the accidental test:
This is rather well known, so briefly: In England a white moth live before coal was extensively used. It became dark gray for about 150 years, but now that the air is not soot filled, it is white again. As there was no "control" group, this could have been just a strange coincidence, due to natural genetic variations.
One controlled experiment was done in Brazil, in the wild, using a stream with waterfall. Below the falls were two types of fish, the bigger ate the smaller, which sexually matured rapidly and as still small, laid few eggs and had few females surviving (on average one) to reproduction age to make the next generation.
Neither of these fish existed in the stream about the waterfall, but some of the small ones were captured and placed there. - Simple, low cost experiment. About 30 years later, the experimenters returned and caught some of the fish from Above the falls, "group A." (and some of the small ones from Below the falls also as "group B" controls.) Both groups of captured fish were then separately raised in tanks with the same stream water flowing thru them for several years. The size at sexual maturity in group B was still just as it was observed 30 years earlier, but group A was much larger at sexual maturity and this sexual maturity was delayed by more than a year in group A, just as Darwinian selection would suggest.
Without any danger of being eaten by the larger fish, the fish above the falls had evolved, selected themselves for delayed sexual maturity when they were much larger and could produced many more eggs.
As I recall sexual maturity age occurred a couple of years later in group A, than in group B, which did not have any changed in the environment to adapt to. In that new environment above falls, Darwin was at work, evolving the fish in group A.
Only difference between the two groups was that the environment of Group A had radically changed and they generically selected for the new environment. THIS IS A CONTROLLED EXPERIMENTAL DEMONSTRATION of Darwinian evolution's "selection of the fittest" (to the environment).
