No one in the world / Ever gets what they want / And that is beautiful /
Everybody dies / Frustrated and sad / And that is beautifulThey Might Be Giants, “Don’t Let’s Start” (1986)
You made it to the last page, or at least you flipped here to see how the book ends. I hope that I’ve shown that combining a strict language like Rust with testing allows you to confidently write and refactor complicated programs. I would definitely encourage you to rewrite these programs in other languages that you know or learn in order to determine what you think makes them a better or worse fit for the task.
I’ve had more than one person say that telling people to write tests is like telling them to eat their vegetables. Maybe that’s so, but if we’re all going to “build reliable and efficient software” like the Rust motto claims, it is incumbent on us to shoulder this burden. Sometimes writing the tests is as much work (or more) as writing the program, but it’s a moral imperative that you learn and apply these skills. I encourage you to go back and read all the tests I’ve written to understand them more and find code you can integrate into your own programs.
Your journey has not ended here; it has only begun. There are more programs to be written and rewritten. Now go make the world a better place by writing good software.