When you say "structurally incapable", what do you mean? They can certainly output the words (e.g. https://github.com/Smaug123/WoofWare.Zoomies/pull/165#issuec... ); do you mean something more along the lines of "testing can prove the presence of bugs, but not their absence", like "you can't know whether you've got a false or true negative"? Because that's also a problem with human reviewers.