Tea-Driven Development

I sometimes get asked whether it’s possible to use Cucumber to test performance. The way to do it is to specify concrete examples of scenarios that the system will find itself in under stress. For example:

Given there are 100,000 users registered on the system
When I create a new account
Then I should be taken to my dashboard within 5ms

or

Given 1000 users are hitting the homepage simultaneously
Then each user should get a response within 2ms

Talking through these kinds of scenarios with your stakeholders will help you to understand where the boundary is for what they consider to be acceptable performance. You might find it hard to get them to be this specific at first, but help them understand that what you’re doing is drawing a line in the sand for the minimum acceptable performance – most of the time the application may be much faster than this. Now you have agreement about this, the next step is to work out how to automate these scenarios, by calling your load testing tool of choice from the Cucumber step definitions.

The key thing is to have Cucumber delegate to the stress testing tool, rather than the other way around. A common mistake people make is to simply point JMeter at existing Cucumber scenarios, but this doesn’t give you the benefit of having the parameters of the performance test documented in readable Cucumber scenarios.

These are not normal kinds of Cucumber tests. You would need to run these against an environment that’s representative of your production hardware, whereas normal behaviour scenarios could be run against any environment. It’s useful to create these scenarios early on during the project and run them against every build so they become constraints that every build must meet as the project progresses.

There are some fascinating discussions going on over on the mailing list for Avdi Grimm’s excellent e-book, Objects on Rails.

Recently, in a discussion about command-query separation and Dan Kubb posted this little piece of beauty:

One convention I use is that query methods are idempotent and return a value, while command methods change state, but they can only return self. This provides a nice fluent interface when working with the objects, and feels quite natural (to me at least).

Feels natural to me too.

We have an old Kenwood Chef A701 that’s hardly out of use in our kitchen. A few days ago, the gearbox went. I bought a reconditioned one on Ebay for £23, and this morning I made the time to do the repair.

As I tinkered away with my screwdriver, I reflected on how grateful I was that the designers of this machine had made sure it could be maintained by an idiot like me. I actually made our A701 by cannibalising two broken machines, and I have always been delighted by how easy it is to work on.

Perhaps it’s my confirmation bias, but it seems that machines like this no longer tend to be designed with maintenance in mind. In our consumer society, we’re encouraged to throw things away rather than repair them, and globalisation ensures that is often the apparently rational economic decision to take: paying a local repair man to fix your DVD player will cost more than popping down to Tesco and buying a new one. Thank goodness for those cheap Chinese factories, eh?

If we don’t design our manufactured goods for maintainability, perhaps it’s no wonder we often feel like we’re swimming against the tide trying to persuade people that it’s important in software.

I really hate passwords. Today I read this, and realised I’m not alone:

me.veekun.com/blog/2011/12/04/fuck-passwords/

If you feel like me, go and have a read. I’m pretty sure it will cheer you up.

Last week I travelled down to London to the BDD Exchange conference. It was a one-day conference organised by Gojko Adzic and I had a great time. I missed Gojko’s talk as I travelled down from my cave in Scotland on the day, but I did arrive in time to see Chris Matt’s excellent lecture on what business analysis really should be about.

I particularly enjoyed the talk from Christian Hassa about teams failing to make BDD work. We can learn the most from failure, and Christian’s thoughtful analysis of what he’s observed in the field as a consultant with TechTalk is useful to any team trying to get the most from these techniques. The message of Christian’s talk very much echoed my own, that the tooling you use is entirely secondary to the collaborative relationship you need to build between the business and technical-facing members of the team. I was interested to learn about the tool, SpecLog, TechTalk are building to help teams with this problem, which seems to have many similar goals to my own Relish. It was nice of Christian to give Relish a name-check in his talk.

My session ran along the same theme as my talk from earlier in the year at Skillsmatter, describing the value of writing acceptance tests at the right level of abstraction, so that they describe business rules rather than implementation details. You can watch the session here.

I want to give you some news about the future of Relish. A lot has happened since we first started the project just over a year ago. Justin quit the project to concentrate on his new role on the RSpec core team, The Cucumber Book went into beta, and my wife gave birth to our second child. All of those things have meant that Relish hasn’t been able to progress as quickly as I’d have ideally liked, so thanks for sticking with us!

I’m still passionate about the vision for Relish, and as I teach training courses on using Cucumber and BDD, it seems to resonate with a lot of people. With The Cucumber Book pretty much behind us now, Relish will come back into focus and the pace will pick up again. I hope to have it launched by the end of the first quarter of 2012.

Here’s a rough outline of what we plan to do:

Usability & Information Architecture Enhancements

I have an IA specialist on the team now, and you may have noticed the first tweaks we’ve been making this week. There’s a lot to catch up, so we’ll focus on this until the existing features are polished to his (and hopefully your) satisfaction. Please let us know how we’re doing as we progress, and let us know if any of the changes annoy or delight you.

If there’s anything specific you’d like to see done that isn’t already logged in UserVoice, please add it there or reply to this post.

Test Results

Relish can’t deliver on the promise of living documentation until the non-technical readers can tell, when they’re looking at a scenario, whether it’s passing or not. We’ll be building a plugin for Cucumber that allows developers and testers to send their test results to Relish, so each scenario can be rendered with a big green tick if it’s passing. This will also enable us to start building all kinds of exciting dashboards for project managers to get a high-level overview of what’s going on.

Commenting / Feedback

Just being able to read features is not enough. I want Relish to be a collaboration tool, and that means that stakeholders should be able to comment on and give feedback about the documentation they’re reading.

RSS / Activity Feeds

People who want to stay up to date with changes to a project will be able to get a nice high-level summary via RSS, and possibly other means too.

Enterprise Install

As the codebase stabilises, I’m becoming increasingly comfortable with the idea of a stand-alone installer for customers who are not happy about having their features stored outside of their firewall. In the new year, I’ll be looking for a couple of friendly enterprise customers to help me shape this. If you’re interested, please get in touch.

Plans & Pricing

Yes, it had to happen eventually

When we come out of private beta (which is still a few months away), it will be with paid accounts for private projects. This is a hard call to make, and I’ll be in working with our beta tester community to get an idea of what they feel is a reasonable price to pay for the service. Public accounts like RSpec and VCR will continue to be free.

As always, I’m keen to hear what you think of these plans. Let me know in the comments.

As requested by JB in the comments to my previous post, here is some data about what happens when a team choose fine-slicing over estimation.

You’re about to see a CFD chart drawn by a team who used BDD to break down every requirement into scenarios before they started hacking on them. The items on the left aren’t actually scenarios in this case, they’re very small user stories which tended to be of a size of about 3-4 scenarios each. The point is, we broke everything down into the smallest pieces of behaviour we could, then re-assembled them into chunks that were meaningful enough to build together.

Rather than using story points to manage the variation in size of stories, we gave each story a value of one point, and used BDD analysis to try to ensure each story was a uniformly small size.

This data was collected over a period of about six months by a team of about eight developers. Their system (a high-volume website) was already live and they were adding features to it.

What strikes me the most is how straight the ‘done’ line is.

Before you write any code, start by brainstorming all the scenarios you’ll need to cover to make the story done. Do this collaboratively with everyone (devs, testers, UX, business people, product owner) who is interested in the story. Don’t try to make them valid Cucumber scenarios, just make a list of them on a whiteboard, index cards, or in a text file.

Now look at all the scenarios you have. Does the product owner really want you to build the product to satisfy all of them? Can you cut any out and defer them as another story to build later? Can you drop any of them altogether? Get rid of as many as you can until the story is as small as you can make it.

Now count how many scenarios you have left, and write that number on the story card. At the end of the iteration, count up how many scenarios you’re managed to deliver in total across all the stories you’ve done, and start using that as your velocity metric. It’s much, much more accurate in my experience than estimated story points. What’s more, the process of exploring the scenarios means you can agree a clear scope for the story before you get started.

Teams who are doing this well are getting things done much more quickly than they did before. Not only do they build a suite of automated regression tests, but they waste a lot less time writing the wrong code because of misunderstood requirements.

Would you like to learn how Behaviour-Driven Development can help your company get better at software development?

I’ve helped several teams learn BDD, and I’ve started to formalise the training I’ve been doing into a set of course modules. The modules aim to provide the foundations for a teamʼs successful adoption of BDD.

We start by immersing the whole team in BDD for a day to get everyone enthusiastic about the process. Then I take the programmers and testers and implement their very first scenario, end-to-end, on their own code. Now that we’ve proved it can be done, I work with project managers, product owners, and development leads, to streamline their agile process to get the best from BDD. We practice collaborative scenario-writing sessions, we learn how to use metrics to track progress, and how Kanban and BDD can fit into your existing agile process.

Please take a look at the course prospectus and get in touch to see how I can help.

I love using Cucumber to help me write software. I almost find it hard to imagine doing it any other way.

I want more people to discover this for themselves, so for the last year or so Aslak and I have been writing a book all about using Cucumber for Behaviour-Driven Development:

We hope we’ve captured some of the passion and sheer enjoyment we get from working with this amazing tool. Whether you’re a complete novice or an experienced Cucumber user, I think you’ll get a lot from the book.

What are you waiting for? Go and get yourself a copy!