BDD Everywhere - don't underestimate your target audience

I have recently moved from doing TDD to BDD, using Scott's excellent SpecUnit.Net with, I have to say, some real success.

BDD was the subject matter being discussed at May's London Altnet beers. After the talk I was discussing with some people about their approach to doing BDD. What was being presented was the idea that BDD specs are useful only at the outer layers of the application and once you get more low level, you should revert to normal style TDD tests.

I don't agree. I have been writing BDD specs for every single class I write, and have recently upgraded our build system (rock on TeamCity) to make the spec reports. Saying BDD is just for the outer layers is ignoring the fact that the users of application know a lot more about their business than you do.

I'll give an example. We are building a system for the traders to view their trades - in what is known in the financial world as a "blotter". Being a WPF application, we build the ViewModels first and then build some sort of data access component. So the requirement is that all the trades made today should be displayed on the blotter when the user refreshes it. Here is a set of specs which say that

when the user refreshes the blotter and no trades have been made today
- should display a message saying there are no trades
- refresh button should be enabled

when the user refreshes the blotter and two trades have been made today
- should be two trades displayed in the blotter
- should display the earlier trade on the first row
- should display the later trade on the second row

So now we write some tests for that, and flesh out our implementation. During this time we create an interface ITradeProvider with a method GetTradesForToday(), and use a mocking framework to stub out the calls to that method using our favourite mocking framework.

Our user/customer/business analyst would definitely find those specs useful, and may even give some feedback or changes, which is great. But what about the TradeProvider implementation? Is that worth doing it for? Some would say no, but I would say. We could start off with something like this:

when loading todays trades
- should load todays trades
- should not load trades from a previous date

That's not really saying anything useful is it. Or is it? Imagine you show this to your users and/or business analysts. They're gonna ask:

"What on earth does that mean? When loading today's trades, should load today's trades? It doesn't make sense! We're a bank, we have loads of trade systems, which one are you getting the trades from?"

"Oh right, well I was going to get them from the MYZ team's Oracle database which we got the trades from on the last project I worked on"

"Ok, that's fine, but that's only going to work for trades outside of Asia. For the trades on the Asian stockmarkets, we're going to have to get the data from the AYN team located in Singapore. They have a web interface for looking at the trades and I think they provide some sort of service for you to retrieve it from"

"Oh OK, thanks! I'll update the specs and get back to you to review them again!"

You may think this is a fairly contrived example, but it's the sort of thing you will come up with time and time again. As developers, we move from project to project all the time, and we often make assumptions based on previous projects. Users, on the other hand, are getting you to build a system to provide value to their business. They are likely to know it a lot better than you! Business Analysts especially have a very detailed knowledge of all the internal systems and what their responsibilities are (though they may not have the kind of deep technical knowledge you have of communications protocols, etc).

So think twice about abandoning BDD for the lower layers of the system. Write the specs, share them, invite everyone you possibly can to review them. The earlier problems are found in a system, the cheaper they are to fix. That's been proven through countless studies.

Evidence Based Scheduling

A co-worker just sent me this article from Joel Spolsky: http://www.joelonsoftware.com/items/2007/10/26.html.

As I'd expect from Joel, it's a very well written article, and definitely worth a read. Has anyone got any experience doing this? I've always thought that tracking individual velocity was a bit fascist, but perhaps it could prove useful?

Also, has anyone tried running a project using FogBugz. Is it any good?

Extension methods make your code more readable

There has been a long standing argument for and against using extension methods. Recently I am on the quest to write code which is as readable as possible. That really is my prime aim - I want someone who is simply scanning my code to be able to, at a high level, understand exactly what is going on in that function. All other aims come second to that (e.g. until a requirement comes along which says otherwise).

Well, six months ago, I would never have made this statement - "Extension methods are a massive help here!". Honestly, they just are. I know people hate them because you can't really tell where the method comes from, and it looks wierd, and it breaks OO because you should inherit to add functionality (well actually, I disagree with that statement being made blindly)...

So I have a function which takes in some dates and returns a status depending on how the dates compare. Here is a simplified version of the function:

public Status GetStatus(DateTime now, DateTime modifiedOn, DateTime createdOn)
{
  if (modifiedOn.Date == now.Date)
    return Status.Amended;
  else if (createdOn.Date == now.Date)
    return Status.New;
  else
    return Status.Unchanged;
}

So what's wrong with that? Well you have no idea what the if statement is actually doing! Tell me, if you scan that quickly, can you tell what the business rule is here? I am pretty sure most people will have to scan that a few times to get what is going on there. I considered adding a comment, but comments are a definite code smell (see DRY) so this is how I changed it (using an extension method)

public Status GetStatus(DateTime now, DateTime modifiedOn, DateTime createdOn)
{
  if (modifiedOn.SameDayAs(now))
    return Status.Amended;
  else if (createdOn.SameDayAs(now))
    return Status.New;
  else
    return Status.Unchanged;
}

Simple but effective methinks. I think it's definitely clearer (though could perhaps be made even better). Do you agree?

A shout out to Benjamin Mitchell

Benjamin has recently started blogging (and about time too!). I have worked as a developer on one of his teams before, and he is a good guy to work for and really knows his stuff. He's one of those PMs who is always looking to improve his team's knowledge, skills and processes.

I hope to see postings about Agile techniques and Lean Development, and hopefully some good anecdotes too!

I am on Twitter

Well, after much nagging by my good friend Mr Norton, followed by a number of people at the AltNet Beers the other night ("what, you aren't on Twitter mate???"), I have finally succumbed and signed up. You can find me at http://twitter.com/nmosafi. I hope to be posting about all my fun and frustrations at work, and hopefully will avoid doing so whilst completely hammered!

Last night's AltNet Beers

Firstly, thanks to Seb for organising the ALT.NET beers conference last night. I had a great time and met some very interesting people who I hope to see at future conferences.

The first topic was on two related questions, which were something along the lines of "why would I use a non-relational database" and "how would I architect a database differently if I was writing more than I was reading".

Personally, I wasn't really getting the question here. The whole thing about "writing more than I read" made no sense to me - why bother writing it if you're never going to read it. The speaker was unable to really identify where his pain points are with his system. I felt that there was an interesting discussion to be had, but the conversation didn't seem to inspire many people and it wasn't carried too far. I would welcome this discussion continuing elsewhere and if it does I would be keen to take part in it.

We talked a bit about document databases here, Ayende naturally getting involved as he has designed (not built, mind) a document database before. The idea is that if you want to store fairly unstructured data, you would use a document database. Again, this isn't something I know much about and I wasn't sure what the benefits of a document database are over, say, storing the document on a file system and then indexing the information you want to search separately (e.g in a relational database for querying, or search appliance for searching).

Note: I was going to discuss this further outside with Ayende but the topic changed to BDD which is something I have recently starting doing so I wanted to hang around for that one! If you're reading then perhaps we can discuss it next time?

So as I said, we moved onto BDD which Ian Cooper summed up excellently with a great analogy, which I won't repeat here. What it bogs down to is that whilst test driven development is about ensuring that we do things right, behaviour driven development is about ensuring that we do the right thing. Given that we had a bunch of Lean/Kanban enthusiasts there, I thought it quite appropriate topic. With BDD you minimise rework by getting things done right the first time, this will naturally help to you can increase throughput and decrease wastage, which is what Lean's all about.

So having recently started a new job (which explains my lack of recent blog posts) I am trying to introduce BDD to the team, using SpecUnit.Net. They don't do TDD at all, and I think BDD is not only easier to adopt but also adds much more value. I am actually new to BDD, having consistenly read about it I'd not had the chance to actually try it on a proper project. I am impressed with the effect and the way it makes you think about your code, so much so that I couldn't see myself not developing in this way ever again!

Anyway I actually had some interesting conversations after the event about BDD. I will try to gather my thoughts about this soon and perhaps capture them on a future blog post.

Silverlight 3… why WPF any more?

Just reading about Silverlight 3 and amazed by the amount of new features which are being added… just look at the list!

It begs the questions is there actually anything left in WPF that Silverlight now can’t do?  It now even supports running outside of the browser!