Last year I had the most wonderful opportunity. I took part in Data Relay, an event in the UK which tours several cities. Wonderful time, but not the focus here. The very first one was held at the National Museum of Computing at Bletchley Park. Without a doubt, you've heard of Alan Turing, Enigma, and his work on the Bombe, an electro-mechanical calculation engine. What you may not have heard of, I sure hadn't, was Colossus, the very first electronic, not mechanical, pure electronic, computer created by Tommy Flowers, a postal worker you probably have never heard of. It's an amazing story, well told there at Bletchley Park. They even have a recreated, fully functional, Colossus there. I strongly recommend you go if you get the opportunity. The secret wasn't even released until 1999, which is incredible.
After a lot of research, I picked up a book on the topic, Colossus: Bletchley Park's Greatest Secret. It has been an amazing read and I recommend this as well. I think the most interesting part of it is not simply how these people built the very first computer, but how they also figured out all the steps in processing that we, sort of, take for granted today. One of the most eye-opening things in the book was the discovery of how important testing and validation was at every step. When they started out, the assumption was, well, of course all the calculations will be correct, it's done by machine after all. Yet, they hadn't run into GIGO (Garbage In, Garbage Out), but they did. The concept of a bug didn't yet exist, but they found them. PEBKAC (Problem Exists Between Keyboard and Chair), also known as operator error, was also not yet a thing, but it's something they found nonetheless. In short, the need for thorough and ongoing testing and validation was cooked into the pie right from the start. And yet, we still, to this day, have a tendency to be dismissive, or least forgetful, about testing and validation.
So, take a lesson from our forefathers & mothers. Set up testing and validation as a fundamental aspect of all your computing needs. It's been there from the beginning and I sure don't see any signs that the need for testing is going away.
PS: Before I let you go and not drop a radio reference, in addition to computing, decryption and the rest, the UK home to amateur radio is also located in Bletchley Park.