Comment by jdlshore | Hacker News Reader

Comment by jdlshore | Hacker News Reader

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"Quite a bit of job postings list TDD as a requirement, in fact, which is silly. It is a bit like requiring vim or emacs."

Sorry, no, TDD isn't like vim or emacs. Your choice of vim or emacs doesn't change the code you produce. TDD does. Whether you agree with TDD or not, it's completely reasonable for a job to require it, just as it's reasonable for a job to require that you know and use MVC (in their app), or Rails, or any other technical solution to a problem.

If I'm hiring somebody, they have to know TDD and apply it, or they won't work for me any more. Period. Just like they have to know what local variables are and use them. Right or wrong, it's a coding/design standard, and it's perfectly reasonable for teams to choose and enforce their coding standards.

Now, that person might be able to convince me that they have something that solves my problem (a need for easily-changed code that does what the programmer intended) better than TDD. Say, a fancy type system. If so, awesome! I'll listen. But "I'll use TDD when I feel like it" ain't gonna cut it.

>If I'm hiring somebody, they have to know TDD and apply it, or they won't work for me any more. Period. Just like they have to know what local variables are and use them. Right or wrong, it's a coding/design standard

TDD is a workflow implementation and not a coding standard per se. This is to say, code written with or without TDD may be completely interchangeable. This is not true of a coding standard.

Coding standards measurably and objectively affect the end product (i.e. "use local variables", "space/tab indentation", "no method greater than 500 lines", "follow an MVC pattern"). Can the same be said for TDD or [insert workflow implementation here]?

This may be a nitpick, but I feel it's important since it highlights why there is such disagreement on this topic.

You and thomasmeeks both said this (that code written with or without TDD may be interchangeable) and I respectfully disagree. Sure, in theory, you could write the same code, but in practice it just doesn't happen. There's a significant difference in the kinds of code that are produced.

Think of it this way. Imagine two different teams. One team has a workflow that involves carefully considering design possibilities and creating design models on paper, and only writing code after those design models have been iterated and refined for a good month.

Another team dismisses that approach as waste, and instead prides themselves on their ability to ship. They start coding on the very first day. Although they care about design, their emphasis is on shipping code, and they would never waste time on modeling.

These are workflow differences. Will the teams produce different code? Of course! They approach the work differently! That's what workflow differences mean.

TDD is a different workflow that produces different code. That difference matters.

(See also this reply elsewhere in this thread: http://news.ycombinator.com/item?id=5334366 )

Edit: I don't mean to say that TDD will lead to good code. Far from it. TDD done badly leads to some gawdawful messes. But TDD done well does lead to code that is qualitatively different than other workflows done well and that difference--the result of using TDD--is useful to me.

Well, yes, if you take it to the ship first vs what amounts to waterfall extreme, there will be profound differences in the code. I suppose if you make it your mission to analyze code to determine whether or not your programmers are using TDD, you could figure it out. But then we're getting into a pretty artificial situation.

Who cares if the code is clean and the project is successful? TDD may be a useful way to get to clean code for /some/, perhaps /most/. But this is not true of /all/. I'm not arguing against its usefulness for someone like you. That's silly, you obviously value it. I'm arguing against the "moral imperative," which is utter nonsense.

TDD is neither necessary nor sufficient for success, and we should stop pretending that it is. I create a class, it has an interface with a purpose, and I test that interface. I don't write tests first, and I don't have trouble writing tests after I write the code. I organize my thoughts on pen and paper, and use very light documentation to test the size and purpose of my methods. The projects I work on are successful, everyone's happy. This is true of several other programmers I work with on a daily basis, but not all. Several also practice TDD, and it works for them.

You're moving the goalposts. I didn't say anything (and I'm pretty sure I never have said) about TDD being a moral imperative. Nor did I say it was necessary for success, nor sufficient.

I said "It's reasonable for a job to require TDD... because the TDD workflow results in a qualitatively different code base." I chose an artificial example of how workflows change code to make the point obvious, but the real-world effect of TDD is night-and-day obvious in my experience.

I value that difference to the point where TDD skill is a core part of my hiring decisions. I'm okay with you making different choices.

Well, sure, I'm not sure I really care about what particular employers require of their employees. I think it is silly, but I doubt you care much about what I think, either. It was a minor point to me (not to you), which is why we've diverged I think. My moral imperative comment is toward the overall topic, not you.

Fair points. I think you've made a good case.

Well, no, TDD doesn't necessarily change the output of a programmer. Even if you require 100% test coverage on every commit (which isn't the point of TDD anyway), there's no way to tell if the tests were written first. It is a "design standard", sure, but so is the nearly universally maligned waterfall process.

Easily changed code that does what the programmer intended is better described as "good design". TDD is a useful design aid, but there's a lot more to good design than just TDD. If you are hitting that requirement, it is because you have good programmers, not because TDD is magic. Fancy type systems don't do much to ensure good design, either. Just like a really nice saw doesn't guarantee a beautiful cabinet.

Interestingly enough, in 2009 Keith Braithwaite concocted a metric that can pretty reliably determine whether a system has been written with TDD or not.

See: http://peripateticaxiom.blogspot.com/2006/05/complexity-and-...

That's cool, and I'm sure the author's conclusions are correct for that code base.

However, the skeptic in me can't help but point out that this is not nearly rigorous enough to say his method can pretty reliably determine TDD vs non TDD code in the general case.

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