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> An objection I hear to this is that you're not just writing tests for yourself, you're writing tests for the others who will need to help maintain your code, perhaps after you're gone. I'm somewhat sympathetic to this, but I would also say that if someone else needs to modify my code, they damn well better first understand it well enough such that they could write tests before changing it (if they deem it necessary). Anything else is just irresponsible.

As someone who has had to fix plenty of legacy code, I have truly appreciated the people who have left me at least some working test suites to run - or just look at - and cursed many others. At the same time, I have generally been handed over code bases with tens or hundreds of thousands of lines, some of which had no useful tests.

If it is irresponsible to try to refactor or fix a codebase without first understanding all of it, it may be even more irresponsible to expect that those who follow in our footsteps will be able to do that, even if they are "gods of programming".

The reason why this is so was hammered home very strongly in Peter Naur's "Programming as Theory Building"[1].

Unless a code base is trivially small or simple, leaving it without meaningful tests instantly creates legacy code. I'll close with an excerpt from the back cover of "Working Effectively with Legacy Code[2].

> Is your code easy to change? Can you get nearly instantaneous feedback when you do change it? Do you understand it? If the answer to any of these questions is no, you have legacy code, and it is draining time and money away from your development efforts.

[1]: https://news.ycombinator.com/item?id=10833278

[2]: https://www.amazon.com/Working-Effectively-Legacy-Robert-Mar...




Yeah, I don't disagree with that, and one of the things I do before I hand off a code base to others is beef up test coverage somewhat, especially in places where the expected behavior of a bit of code might need to be codified to a certain extent.

Regarding your "legacy code" quotes: I don't write code that isn't easy to change, or easy to read. If I write code that's hard to read, I delete it and start again. If I absolutely cannot write something that's easy to read, I write tests around it and document the hell out of it (I'm iffy on comments and docs as well, because they _always_ end up out of date, and then are more of a hindrance than no comments at all).

I think I'm pretty good at what I do, but I wouldn't consider myself a "god of programming". Writing clear, concise code isn't hard. It really really really isn't. In my experience, the main blocker to that is ridiculous time lines and pressure to ship. I know it can be hard to push back against that pressure, but you owe it to yourself, future maintainers of your code, and the company you work for (even if the company doesn't realize or appreciate it at the time) to slow things down and do things the right way. A former colleague used to say, "It's not right because it works; it works because it's right". Just because a bit of code produces the output you want, it doesn't mean it's right. Write the right code -- readable, maintainable, verifiable, testable -- and you don't even need to worry about it working, because of course it will.

I lean on type systems heavily. If I were writing python or ruby, I'd have 10x as much test code as application code, because I just do not believe you can trust a dynamic/weakly-typed language without them. This is why I avoid such languages; I think any gains in rapid development that you get from such languages are quickly wiped out by the need to write extensive tests, or, lacking those, all the bugs that come up because you don't have them.

These days I write most things in scala, if I can. No, it's not a perfect language (honestly, I'd say a half to two thirds of it is crap, but the rest of it is amazing), but it has a strong type system that lets you lean on the compiler so much more than many other languages. Simply the fact that it compiles gives me much higher confidence than with most other languages.




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