[Code Friday] Tasty, tasty behaviour-driven development

[maradydd]

By way of sfllaw, a development paradigm I had not previously known about, and tool for developing in this fashion. Holy shmoley. I agree with Bill Tozier, I want this for Python yesterday.

Behaviour-driven development is basically test-driven development on steroids: it takes the principle we like to cite, "write your man pages first!", and hooks it right into the test-driven development cycle, except now you're developing one behaviour at a time, so you can write your tests piece by piece and have individual chunks of the system piece by piece. I like TDD, but sometimes I have to write code fast (and yes, TDD always ends up saving me time in the end, but we've all had those projects where OMG EVERYTHING IS ON FIRE AND THERE'S NOT TIME TO DO IT RIGHT. Behaviour-driven development eliminates your excuses to not do it right: you're producing code as discrete functional units, complete with tests to prove that they are correctly functioning functional units, and you're producing it fast enough to keep management/the client happy. (Clients are sometimes not happy when the first week of work goes into building the unit test suite. Yes, yes, I know, that week of work saves a month or more later on down the line. Some of my clients are no longer my clients for a reason.)

Behaviour-driven development is also a great tool for the "design the UI first" school of programming, and any project that doesn't follow that school of programming is doing it wrong. (Think of it this way: if you're writing a library, design the API first -- that is to say, write the man page first. If you're writing a web application, mock up the user interface, figure out what the damn thing's going to look like and do all your changing-your-mind about how the UI is going to behave before you start laying down AJAX requests.)

Also courtesy sfllaw, a talk by Ben Mabey explaining not only these ideas but the business decisions which motivate behaviour-driven development. This is a really great overview and I strongly encourage any programmer with a pragmatic spirit -- or, even better, an entrepreneurial one -- to block out half an hour of your time to watch it.

Alas and alack, Cucumber is not available for Python yet, and from what I've seen, I really like the way it works. It apparently can be used with PHP, but I really would prefer to avoid PHP if at all possible; my preferred style is just way too functional these days to blend well with PHP. (I've developed a thing for continuation-passing style in the last month or so.) This may end up being the thing that finally motivates me to learn Ruby. I have a little side project going on right now that has a web-application-framework-shaped hole in it, and I had been planning on using Django, but given that it's going to be a Javascript-heavy front end with likely a healthy dose of script.aculo.us, Rails could be a better tool for the job. I'll need to decide if I like how Rails talks to databases; I'm madly in love with the way Django does it and anything less will be a major disappointment, so this is definitely a factor to consider. (Current Rails devs, your input is welcome -- I know very little about your framework. I used to be cranky about the lack of integration with Apache, but there's mod_rails these days and I assume that removes a lot of the reasons I had for bitching.)

And I'd have real continuations. That's always a plus.

Decisions, decisions. But I do like the fact that tools like this exist at all; it's me who needs to get over my uncanny-valley problem with Ruby.

(karnythia, thewayoftheid, tanyad, I'm not talking about the project I'm doing for y'all, this is a different project. So many irons in the fire!)

Comments

[maradydd.livejournal.com]

The problem I keep running into with Ruby is that it's so Python-like that I run into this uncanny-valley problem with the idioms. This is, however, a failure on my part with respect to Ruby.

There are a bunch of considerations to take into account when deciding what fits best in that web-application-framework-shaped hole: what the team members are most experienced with ($collaborator knows no Python yet, but might know some Ruby; I know very little Ruby and buggerall about Rails, but there are tutorials), what will be the best tool for the job with respect to features, what will be the best tool for the job with respect to maintenance and the Next Jackass Problem, just how badly I want to use this BDD tool, &c.

[digitalsidhe.livejournal.com]

The problem I keep running into with Ruby is that it's so Python-like that I run into this uncanny-valley problem with the idioms.

I can totally understand that. It's part of what I was getting at in my last paragraph. "Uncanny valley" is actually a pretty good phrase to describe how similar the two are (and yet how different).

just how badly I want to use this BDD tool, &c.

Which one? Cucumber? It's available for Rails. (I'm misunderstanding, aren't I?)

(Oh, and as far as Ruby tutorials? If you're as much like me as I think you are, you'll find why's Poignant Guide to Ruby to be interesting, but quickly infuriating and not very useful. It's fun to read the first 2 or 3 chapters, but by the end of them, I was going, "That's amusing as all hell, and I love the cartoon foxes screaming about chunky bacon,, but it's not actually teaching me to program in this language nearly as quickly as a more left-brained guide would.")

[maradydd.livejournal.com]

(I'm misunderstanding, aren't I?)

Yes. :) "Compatible with Cucumber" is a plus for Ruby and a minus for Python. Though, looking further into the Cucumber docs, it looks like there's a way to use it with some other tools for language-agnostic, outside-in Web application development; I may end up trying this, and if I do, I'll report back what I find out.

Thanks for the tip on the tutorial, I'll have a look. :)