>you can't test that they work. Sure you can: one needn't test the full exact as-will-be deployed assembly to have confidence a system will work. Systems can b

>you can't test that they work. Sure you can: one needn't test the full exact as-will-be deployed assembly to have confidence a system will work. Systems can be tested in parts or with surrogates. Will the exact system in the exact conditions have been tried? No - but that's not really the goal; the goal of testing is only ever achieving an adequate[0] confidence of success in actual use. [0] A situationally defined term.