I wonder how can scientists trust closed source programs/softwares. How can they be sure there aren't bugs that return a wrong output every now and then? Assuming they use some kind of extensive tests that figures out whether the program behaves as it should, how can they be sure that the programs aren't going to suffer from bugs and stuff like that (malicious code included) in further releases? Are there any kind of extensive tests performed on software that are generally used in branches of physics or any other science involving data analysis? Blindly trusting a closed source program seems to go against scientific mindset to me.