Thursday, 3 November 2016

Software Engineering : Test Driven Development (TDD)

"Test-first fundamentalism is like abstinence-only sex ed:
An unrealistic, ineffective morality campaign for self-loathing and shaming."
 - David Heinemeier Hansson, 2014

I was very recently inflicted a case of TDD... I didn't like it, like the bad taste of medicine it lingered on my mind, so that I had to do some reading to even wrap my mind around the concept, and in wrapping around the idea my mind is made up to throttle it out of existence anywhere near me.

I come from the very much more formal days of development, from systems where you had very limited resources, there wasn't space to run a test suit on top of your editor next to your compiler, indeed the systems I learned to program with one had to chose to swap the editor and compiler and even a separate linker in and out of memory to achieve your build.

Taking that amount of time to do a build, it makes you learn from your mistakes quickly.  Such that I find myself now a rounded, and I'd like to think good, programmer.  I'm not the best, I've met a few of the best, but I'm good.

So combine a propensity to think about the problem and the drive to achieve a solution in code quickly, I'm used to thinking about testing after the fact, used to at least in part sticking to the old mantra of "Analyse -> Design -> Implement -> Test -> Document", with each step feeding each other.

For you see development today is not serial any more, you don't have time to stop and think, you perhaps should.  This was perhaps the only positive I see in employing TDD, and indeed it was one of the positives myself and the chap I was speaking to commonly came to, it makes you slow down and think about a problem.

However, if you're a traditional programmer, a goal orientated programmer, like myself, you've a plethora of patterns, design and experience to draw upon, which tell you your goal is achievable a certain way.

Design patterns and library implementation style, and simple rote learning of a path to a solution can drive development, peer review can share you ideas and impart new ideas on yourself, so why should you let the test; something which intrinsically feels like the end result, or the last step before accepting the solution; drive development of the solution?

I really can't think of a reason, and have now to take to the words of brighter stars than myself to express how it made me feel...

It felt like a litmus test, something being used to make me feel unprofessional, in a single trivial class, which should have taken five minutes to write and check over, an hours struggle ensued where hammer blow by hammer blow by the grace of TDD I was held up as a heretic.  "Thou dost not know TDD", the little voice in the back of my mind said, and I felt low.

But beyond how I felt, it seemed so inefficient to work in that manner, when one has programmed or engineered or done any task for long enough we build a reflect memory of how to achieve that task again, walking, reading, driving, programming... All these life goals and skills we just pick up.

Training in Karate was very much like this, one had to teach people to do things with care... 10 Print Hello 20 goto 10... Then we had to show them how to do more complex packaging and reuse of code procedure example(p_value : integer) and eventually we could let them free fight int main () { std::cout << "Hello World!" << std::endl; } and during this building up we let them drop the earlier teachings into their muscle memory, into their subconscious, we exercised, but didn't re-teach the same things, didn't cover the same ground.

Yet that coverage of the same ground is exactly where I felt TDD was taking me, and it seems to be the consensus among other "non believers" as to where it takes you, to write a test exercising your code, then to iterate over changes, sure it drives efficient code in the end, it drives out tested code before a single functional line has been written, but was it the quickest way to the same solution?

For a seasoned, experienced programmer like myself, No, No it was not, it bypassed so much of my experience as to know my self-confidence to literally brow beat me into worry.

I therefore stand and say "I do not write software test-first", and this is based on having to learn in an environment where one could not afford the processor cycles or memory to test, nor did one have bosses open to the concept of micro-design and iteratively pawing over code, one had to get the job done, and get it right or not have a role any longer.

Huib Schoots over at AgileRecord can be quoted as writing "TDD is a method of learning while writing clean, maintainable, highquality code", I would have to paraphrase that statement as "a method of learning today from scratch whilst writing modern, clean, maintainable, highquality code"  for a programmer setting out to learn their craft today is never going to have the benefit of the environment I learned in, they're not going to catch up to my twenty plus years of industry exposure and some thirty years academic experience on the topic.  They need to learn, and if teaching test proves a good starting point so be it, however, once the learning curve plateau is reached, even before, one has to question whether you need to take that next step back, step away from micromanaging the development process and evolving your code to just delivering the final product in a working form.*

Others on the topic:

* Please note, with this statement I am not advocating stagnation, and not saying that old-boys like myself are superior, however, TDD appears to me to dismiss any other way of working, to a fault and in my opinion its own ultimate flaw is itself, test your development, but don't drive your development with the test, you will seriously only be putting the cart before the horse.

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