I'd try to test smaller chunks of code for validity. If any block of code is longer than 12 lines, I get nervous that I don't understand what it's doing. Refact

I'd try to test smaller chunks of code for validity. If any block of code is longer than 12 lines, I get nervous that I don't understand what it's doing. Refactor your code into functions as you confirm the code behaves as expected in the interpreter. It's very difficult to write automated tests when all logic is in outer scope rather than chunked into functions.