Are coding katas really worth it?

Driving out feature ambiguity

Cucumber features are very useful. The ability to spec out what the customer wants in detail in a format they can read and understand really helps to communicatate what needs to be done. This combined with the ability to execute the feature to ensure that it is completed correctly catches many bugs and incorrect assumptions.

However there is one area of bugs that features don’t catch so well, and even cause to some extent. These bugs are built right into the text in the form of ambiguity, sometimes through the constraint of features being executable.

This came up recently in a conversation with James and Enrique at Eden Development about James’ apprentice task, the Snakes and Ladders Kata. It turns out that the text of one of the features runs against the commonly understood way that Snakes and Ladders works:

Scenario: Win the game
    Given player 1 is on position 97
    And player 1 rolls 3
    Then player 1 has won the game

Question: is that a valid scenario? Given the commonly understand rules of Snakes and Ladders, you cannot just start on position 97. Implementing it as written complicates the domain model.

How do you implement the first step? Do you go for a simple:

Given /^player (.*?) is on position (.*?)$/ do |player, position|
  @game.set_player_position(player, position)
end

The potential issue with this is that you are exposing a method that in real life won’t get called, just to set up a test. It’s also tying your model down to a particular structure, by implying that the game stores an arbitraty position variable for a player. This might not be the best way to model the problem.

The other option is to change the scenario such that the “Win the game” is tested in a similar way to the following:

Scenario: Win the game
    Given a game is started with two players
    And the following dice are rolled:
      |3|
      |4|
      |5|
      |5|
      (etc.)
    Then player 1 has won the game

That satisfies our understand of Snakes and Ladders, and gives us more freedom in our domain model. In this case, we simply modify the agreed scenario in the code and sidestep the problem.

Right? Wrong.

The important thing to remember is that the customer is always right about how the software should behave, even when it violates our commonly understood assumptions about the world. The software they want you to build might require a different implementation of Snakes and Ladders. They might have a 3 year-old daughter they’re planning to play the game with, who always wants to be given a headstart. In this case, we’ve not delivered what they want, simply because it makes life easier for us. We’ve let our assumptions and our concerns for good design drive out the features, rather than letting the features drive our design.

There’s another possibility: when the customer wrote this scenario, they simply used “starts on position X” as a shortcut and don’t really care if it’s possible to do this in real life. In this case, we can work with them to write the scenario so as not to cheapen our design for the sake of easier feature writing.

The key insight: there’s no way that we can know which it is from reading the scenario. We have to ask the customer and drive out the ambiguity in the feature.

We mustn’t let the necessary constraints of executable features build ambiguity into your conversations about what the customer really wants. And we must be constantly talking to the customer all the way through the iteration, especially if they’re not on site.

You might think “It’s only Snakes and Ladders, what does it matter?” It matters a great deal: situations like this come up regularly in real life projects. Practising how to deal with these issues and the conversations that result is one of the many powerful things you gain by doing katas.

What’s your take on the above problem? Have you come across it in real life?

Snakes and Ladders Kata

I’ve been mentoring a couple of guys at Eden over the last few weeks. They’ve been working away on the Binary Chop kata and it’s been generating some interesting discussions on what Test Driven Development actually is, and how to do it properly.

More on that in another post; today I want to outline the next task I’ve got prepared. Continuing on with the TDD theme, I’ve prepared a basic specification of Snakes and Ladders, using Cucumber features to give a simple outline.

The task is to take this basic github repository and prepare a kata which fully implements the features given using TDD.

If you’d like to try it yourself, feel free! Any patches to the features would be most welcome. Let me know how you get on.

UPDATE: I’ve fixed a bug in the features (thanks nickh) and merged in a patch from ohthatjames to provide some basic support files.

UPDATE: Olly Legg commited a couple of tweaks and improvements.

Blogging again after a long hiatus

It has been a long time since I wrote on this blog. Roughly 10% of the world’s population wasn’t even alive yet when I last posted - that’s sobering!

How to lead your life

Some of us might say that we aren’t leaders. However, we are all leaders of at least one thing: our own lives. We determine the way that we should go, what we spend today doing. If we allow our life to happen to us, then the our lives will be determined by the whim of others and not ourselves.

It’s quite possible for us to lead our lives without actually leading our lives, so in 2017 I’ve decided to try to do better at living a life that counts.

As a first step, I spent the first part of the week trying to simplify my life down to the core essence of what I want to focus on. Here’s my list today:

• Build relationship with Ellie and the kids.
• Continue my current fitness training regime.
• Try to live according to the teaching of Jesus in my community. This is separate from what people might think of as “being a Christian”, but that’s a topic for another time.
• Work to create systems that make people’s lives better. I’m currently doing this for money for various organisations, and by creating fun video games.
• Teach and train people how to lead others and be amazing - that’s why I’m writing this post.
• Improve my writing skills and range.

If something I’m doing doesn’t fit into this list, then I’ve decided to work towards removing it from my life.

More than ever in this present age of mass distraction, our headspace is the key limiting factor to productivity and achievement. It’s a resource to be managed and conserved. I’m only a week in, but have benefited hugely from the reduced focus already, and my job satisfaction is much improved.

If you made a list such as the one above, what would be on it? What should we remove in order to conserve headspace, and to focus on what counts?

Introducing Morning Pages

I’ve written before about the value of Morning Pages - a way of clearing your head in the mornings by writing down three pages on everything you’re thinking and feeling.

In order to write my words, I used 750words.com for a number of years, but I’ve become a little disenfranchised with having private writings stored permanently in the cloud. I also write fastest in vim, which means writing into a website slows me down. What I really wanted was to store my words privately on my laptop, and yet also include a public incentive system: this is what made 750words.com so effective at keeping me motivated.

gem install morning-pages

The result is the morning-pages gem. The gem has been available for a while, but starting today it’ll record your progress on a central website. It only ever uploads aggregate statistics: the code is open source so you can check it out for yourself to make sure.

For instructions, see the accompanying website. There aren’t any aggregate stats yet, but in future you’ll be able to see any word streaks, what times of day you are most likely to write, etc. I’ve got some nice ideas for visualisation which I’ll add as time permits: if you’re impatient you can always fork the website code and create whatever stats you want!

What do I use my words for?

Writing three pages is still something I try and do each day: I had a 170 day streak going at one point. I use my words to plan and order my day, to negotiate with myself about what I can realistically achieve, and for prayer and meditation - I’ve found I pray best at the point of a metaphorical pen.

Do you try to write each day? What do you use your words for?