Posts tagged ‘teaching programming’

Note: this was originally posted on Praqma’s blog

The life of a consultant has drawn me back, but perhaps surprisingly, this time it’s not a return to my one-person firm. Rather than reinvigorating Bache Consulting, I’ve decided to join Praqma, the Continuous Delivery and DevOps Company. I was pretty happy at Pagero. I’ve successfully run my own business before. Some of my friends think I’m crazy to leave a good job with a great team working with exciting technologies. Others think I’m crazy to not want to be my own boss again.

So why Praqma?

Code that gets used

Writing code is really good fun. Writing code that people actually use is even more fun. That’s one of the reasons I like setting up Continuous Delivery pipelines for a development organization. Anything you change gets used almost straight away, and you get feedback from people around you all the time. It’s a fantastic feeling when you implement something that means the whole development team can move forward more quickly, confident in the quality of what they’re producing.

The kind of work I’m talking about is setting up build and delivery pipelines using a CI tool like Jenkins or Go.CD. It’s automating all the installation steps needed for a new machine in a staging environment. It’s moving all the code into a modern DVCS like Git, and setting up automated processes to help keep the master branch in a working state.

In my experience, this kind of work gives you the opportunity to raise the productivity of so many other people, it can have far more impact than if you stayed in your cube hacking on a product by yourself.

Amplify your effect

Another activity I really enjoy is facilitating and teaching. Preferably that kind of teaching that you do from the back of the room, where your job is to set up situations where learning is inevitable. I’ve spent a lot of time over the years facilitating Coding Dojo meetings, and more recently I’ve started doing more Mob Programming with teams. My aim is usually to get people to experience effective development practices like Test-Driven Development (TDD), and understand the difference it makes.

Again, the focus is on raising the productivity of other people, this time through coaching and training. Actually, I’m not directly raising anyone’s skill level. What I’m trying to do is to activate people’s innate motivation to want to get better at their job, and showing them a way to do that. It goes hand in hand with making the technical environment they’re working in conducive to good practice by having good automation infrastructure. TDD makes a lot more sense when you have a CI system to run the tests, and information radiators that show you when the build is broken.

Raise your game

So I’ve just joined Praqma, which is a consultancy focused on Continuous Delivery and DevOps. I now have a host of colleagues who are also really skilled with this kind of technical coaching role I just talked about, and know how much fun it can be. We’re really good with tools like Jenkins, Docker, Artifactory and Git, we set up Continuous Delivery pipelines, and we coach developers in how to use them. What we’re finding though, is that once we’ve got all that set up, the next step usually involves improving the automated testing in the pipeline. We need to be there coaching developers in TDD, and getting automated system tests set up.

That’s where I’m hoping my joining Praqma will help us all to raise our game. Starting with the consulting work Praqma already does, which of course lays the foundations with Continuous Delivery, we can start doing more coaching in test automation. I have long experience of that, teaching TDD in particular. I have much less experience of some of the other things that Praqma does though. What I’m hoping is that by working together with the other consultants at Praqma, and collectively sharing our toolboxes, we can all have more fun and achieve more for our clients. I don’t mind working alone at a client, I’ve done it before, but having colleagues is so much better. We’re going to have a blast!

Join us

Praqma is expanding throughout Scandinavia right now, with offices in places like Copenhagen, Oslo and Stockholm already. I’m starting the office in Göteborg. If the kind of technical coach role I’ve just described appeals to you, I’d be delighted to tell you more, do send a mail, emily.bache@praqma.com, or a tweet, I’m @emilybache.

We’re not only looking for senior people with lots of experience, by the way. If you have the right attitude and willingness to learn, that can take you a long way. We’re looking for people to join Praqma at all our offices, please send your resume and a covering letter to jobs@praqma.com. Of course I’d be particularly pleased if you wanted to join me in Göteborg.

Last week I met Woody Zuill when he came to Göteborg to give a workshop about Mob Programming.  At first glance mobbing seems really innefficient. You have a whole team of maybe 6-7 people sitting together all day, every day, programming at one computer. How could that possibly be a productive way to work?

I’m pretty intrigued by the idea. It reminds me of the reaction people had to eXtreme Programming when they first heard about it back in like 2000. Is it just an off-putting name for something that could actually be quite brilliant? There are certainly some interesting people who I respect, talking warmly about it. The thing is, when it comes to working together with others, programming at one computer, I’ve had some mixed results. Sometimes good, sometimes less good.

I’ve done some pair programming, and found it worked well with some people and not others. It’s generally worked much better when I’ve paired with someone who has a lot of useful knowledge that I’ve lacked. Either about the language and frameworks we’re using, or about how the software will be used – ie the problem domain. I’ve found it’s worked a lot less well in other situations, with other people. I find it all too easy to hog the keyboard, basically. So I do pair, but not that often.

With ‘Randori’ style coding dojos, the idea is that you have a pair at the front who code, and switch one person every 5-7 minutes, or every test case. I’ve facilitated a lot of these sessions, and I find them especially useful for quickly getting a group of people new to TDD all up and running and pointed in the same direction. Recently I’ve been doing it only for the first session or two, instead having everyone working in pairs most of the time. As a facilitator, this is far easier to handle – much less stressful. Managing the interactions in a bigger group is difficult, both to keep the discussions on track, answer questions about the exercise, and to maintain the pair switching. I also find the person at the keyboard easily gets stressed and intimidated by having everyone watching them, and often writes worse code than they are capable of. So I do facilitate whole-group Randori sessions, but not that often.

So I wanted to find out if mob programming had similar strengths and weaknesses. In what situations does it excel, and when are you better off pairing or working alone? Would I find it stressful, like a Randori? Would I want to drive most of the time, as in pair programming?

Woody turns out to be a really gentle person, about as far away from a ‘hard sell’ as you can get. He facilitaed the session masterfully, mixing theory and practice, telling us stories about what he’s found to work and why. I am confident he knows a lot about software development in general, mob programming in particular, and he is very humble about it.

The most important insight I gained from the session, was that I need to get good at ‘strong-style pairing’. That seems to me to be at the heart of what makes Mob programming work, and not be stressful like the Randori sessions I’ve been doing. I think it will also help me to get pair programming to work well in a wider variety of situations.

I have heard about ‘strong-style pairing’ before, from Llewellyn Falco, who invented it, but I havn’t really experienced it very much before, or understood how important it is. Do go read his blog post about it, for a fuller explanation of what I’m talking about.

The basic idea is “For an idea to go from your head into the computer it MUST go through someone else’s hands”. That forces you to express your ideas really clearly, in words, first. That is actually pretty difficult when you havn’t done it much before. The thing is, that if you do that, then you open up your programming ideas for discussion, critique, and improvement, in a way that doesn’t happen if they go straight from your head through your own hands into the computer. I think if I get better at ‘strong-style pairing’ it will help me not only with Mob programming, but also with pairing and facilitating Randori dojo sessions. Probably also with programming generally.

Pairing has worked best for me when I’ve been driving, and my navigator is good at expressing ideas for me to understand and then type. I think I need to get good at that navigator role for the times when I’m the one with more ideas. I need to learn that when I think ‘I have an idea about to solve this problem!’ I should hand over the keyboard, not grab it. I need to learn to express my coding ideas verbally. Then I will be able to pair productively with a wider range of people.

Randori sessions are much less stressful if the driver has less to do. If the responsibility is shared more evenly with the Navigator, then I think everyone will write better code. As a facilitator, I have less group dynamics to worry about if the designated navigator is in control, and everyone else talks less. (Woody advised that, at least at first, you should ban anyone else in the mob from giving the Driver ideas about what to type, so the Navigator learns the role.)

So thanks, Woody, for taking the time to come to Göteborg, sharing your experiences and facilitating a great workshop. I learnt a lot, and I think Mob Programming and Strong-style pairing could quite possibly be some of those brilliant ideas that change the way I write code, for the better.

I’ve been interested for a while in the relationship between TDD and good design for a while, and the  SOLID principles of Object Oriented Design in particular. I’ve got this set of 4 “Racing Car” exercises that I originally got from Luca Minudel, that I’ve done in coding dojos with lots of different groups. If you’ve never done them, I do recommend getting your editor out and having a go, at least at the first one. I think you get a much better understanding of the SOLID principles when you both know the theory, and have experienced them in actual code.

I find it interesting that in the starting code for each of the four Katas there are design flaws that make it awkward to write unit tests for the code. You can directly point to violations of one or more of the SOLID principles. In particular for the Dependency Inversion Principle, it seems to me there is a very direct link with testability. If you have a fixed dependency to a concrete class, that is always going to be harder to isolate for a unit test, and the Tyre Pressure exercise shows this quite clearly.

What bothers me about the 4 original exercises is that there are actually 5 SOLID principles, and none of them really has a problem with the Liskov Substitution Principle. So I have designed a new exercise! It’s called “Leaderboard” and I’ve put it in the same git repository as the other four.

I tried it out last week in a coding dojo with my colleagues at Pagero, and it seemed to work pretty well. The idea is that the Liskov principle violation means you can’t propely test the Leaderboard class with test data that only uses the base class “Driver”, you have to add tests using a “SelfDrivingCar”. (Ok, I confess, I’ve taken some liberties with what’s likely in formula 1 racing!) Liskov says that your client code (ie Leaderboard) shouldn’t need to know if it has been given a base class or a subclass, they should be totally substitutable. So again, I’m finding a link between testability and good design.

Currently the exercise is only available in Scala, Python and Java, so I’m very open to pull requests for translations into other programming languages. Do add a comment here or on github if you try my new Kata.

I was recently at the Software Craftsmanship Conference at Bletchley Park in the UK. This is a one-day conference for software developers, attended by around 150 programmers. All proceeds from the event go to support Bletchley Park, which is of historical interest to programmers in particular – the site where Alan Turing and others cracked the enigma code in the 2nd world war. It was the fifth time this conference has been run, and the first time I attended. This is a short experience report.

In the morning I ran a workshop titled “Outside-In, with or without Mocks?“. We were about 50 people in the Ballroom in the Mansion, a very grand room, and it was really great to see so many people working in pairs at laptops, puzzling over some code and tests and how to do Test Driven Development. We were looking at a code kata I’ve designed called “Train Reservation“. It’s in no way a beginner exercise, and the crowd at Bletchley seemed to get on with it rather well on the whole. I’m just sorry I didn’t get round to talk to each pair very often, with 24 pairs I only had a couple of conversations with each during the 2 hour session!

I set up the exercise more or less to force people to use some kind of mock, fake or stub to replace the Booking Reference Service and the Train Data Service, because I am interested in how different people use these. I’ve observed that some programmers avoid using test doubles whenever possible, while others use them frequently. I’ve also observed that some people prefer to work outside-in, starting with a guiding test, while others prefer to start with the business rules at the heart of the problem and work outwards from there. At this particular workshop, there were all sorts of approaches being used. Some started with the guiding test and stubbed the services. Others started with the business logic around the seat selection rules. Different approaches, as I had hoped! Overall I feel encouraged that this exercise is a useful one, and people seemed to get on better with it than the last time I ran it, at XP2013. It’s till rather too big of a problem to tackle in a half day workshop though. I’ll be updating it some more before I run it again, although I don’t have any fixed plans for when that will be yet.

In the afternoon, I went to a session by Ivan Moore and Mike Hill, “Inheritance to Composition“. They gave us a demo of this particular refactoring using a very simple codebase, before launching us into a much more complex one – Fitnesse (starting from the branch “revised-ResponderFactory”). The idea was to take some classes that were using Inheritance – specifically the Template Method pattern – and convert them to instead use Composition – specifically the Strategy pattern. They also helpfully provided us with a sheet of instructions – 6 steps to complete the refactoring with minimal risk and code breakage.

My pair and I got on fairly well with the refactoring, and by the end of the session we were on step 5 with the goal in sight. The experience was of using Eclipse’s refactoring tools extensively, and relying a great deal on the compiler. The tests we had to lean on took a minute and a half to run, and actually, the tests for the classes we were working on were more mini-integration tests than unit tests as such. It meant there were relatively few updates to the tests as we did the refactoring, but the feedback loop was slow. I thought that was really interesting, and was wondering how the experience of the refactoring would change in a language like Python. There you don’t have a compiler, or very much help from refactoring tools.

So after the workshop, I set about trying to construct a similar problem in Python. Perhaps understandably, I didn’t want to translate the whole of Fitnesse to Python, (!), so I tried to re-write only the elements of it essential to this exercise. You can have a look at what I’ve come up with in my new repo “WikiSearchKata“. I’m still working on preparing this properly as an exercise, (the instructions are still rather thin), but I plan to try it out at a GothPy meeting sometime soon.

After the conference sessions had ended, we were treated to a guided tour of the National Museum of Computing which was for me, the highlight of the day! Our enthusiastic guide showed us all sorts of ancient computers and storage devices and punch cards… a few I recognized from my childhood. My dad used to bring home old punch cards and my mum used to write her shopping lists on them when she went to the supermarket. They had a 48K ZX spectrum with rubber keys – just the same as the one I wrote my first program on! They had a CRAY supercomputer similar to the one I remember seeing once when I visited my dad’s work as a child. It’s a similar size to (the outside view of) a Tardis, with a big red button on the front. I don’t think we found out what the red button does, but the guide did say we probably have more computing power in the smartphone in our pocket! I found the changes in storage capacity actually even more impressive. They had these washing-machine sized boxes and dinner-plate sized metal disks that together made a hard drive. I think it held something like 4K.

The highlight of the tour was the WITCH computer – the oldest working computer in the world. It was brilliant! You could actually see what it was doing while it read in a paper tape punched with holes – the program – and loaded values into registries and did calculations. It made this fantastic whirring noise as it ran, and has all these little whizzy flashing lights. It works in decimal rather than binary, so each number is represented by a little “dekatron” – a glass tube with a red light inside, that moves between positions 0-9 in a circle. So you can read which number is in the registry by looking at the position of each light in the array. They also had this little button you could press to make it step through the program one instruction at a time. I got to press it, and single-step a computer from 1951!

Compared with other conferences I’ve been too, this one was rather short, just one day, and with rather long sessions – half or whole day. It was hard work coding and facilitating all day, but in general very interesting people and coding exercises. A second day would have made it more worthwhile my making the trip. In any case, my thanks to Jon Dickinson for organizing it.

Do you automatically get better design with TDD? Does an otherwise average software developer produce superior designs if they write the tests first rather than afterwards? Does it make a difference what style of TDD you use?

incident #1

I was at a session at XP2012 with J.B. Rainsberger called “Architecture without Trying”. He demonstrated how he could develop a software system for Point-of-Sale terminals using TDD, and how the design naturally tended towards an MVC pattern as he did it. He claimed that purely by doing TDD, and focussing on two things, (removing duplication and improving names) that a good design would naturally emerge.

incident #2

I heard a talk by Luca Minudel at Agile Testing Days 2011 called “TDD with Mock Objects: Design Principles and Emergent Properties”. He was talking about a study he had done where he got people with varying levels of experience at TDD to do four short exercises. He also got them to answer a questionnaire about their knowledge of SOLID principles, and TDD. He then evaluated how well the designs they came up with in the exercises adhered to SOLID principles, and tried to correlate that with their TDD skill. He found that the people skilled in TDD did better in the exercises than those who only knew the theory of SOLID principles. The practice of TDD seems to help people with design. Luca also found that those more experienced with the London School of TDD did even better than other TDDers.

incident #3

I was working at a client recently when I met a developer from a different department. He came to see me several times over a period of a couple of weeks, and asked for advice about TDD. On about his fourth visit he told me he had written some code and now it was basically working, he wanted to write tests for it. He said he was having difficulty since he’d written a lot of static “helper” methods. I advised him that static methods make code quite hard to test, and can often be a sign of a not very good object oriented design.

He suggested we should invest in a fancy mocking tool that would enable him to easily replace these static methods in the tests. I told him a better investment would be for him to learn to write the tests first, get better at OO design, and not use static methods in the first place. I was probably a bit blunt, and he was quite polite, all things considered. He protested that he shouldn’t have to change the production code in order to get it under test, then left. That was the last time he came to me for advice.

Discussion

So does doing TDD guarantee better design? Well it should certainly help. I’ve presented before about the way TDD gives you early feedback on your design and plenty of opportunities to refactor. It’s less help though if you don’t know what a good design looks like in the first place. I think J.B. goes too far in his claims – if you don’t know MVC or SOLID principles then I’d be surprised if they started turning up in your code with any consistency.

No tool nor technique can survive inadequately trained developers” 

(A quote attributed to Steve Freeman). I think you do need to invest in learning good design techniques independently of TDD. If you lack basic OO design skills you probably won’t be able to do TDD in the first place, London School or otherwise.

I’ve been learning and improving my practice of TDD, including the London School, for many years now, and I was intrigued by Luca’s claims that it led to better adherence to SOLID principles than classic TDD. The London School involves an outside-in approach to design, that makes heavy use of mocks to check interactions between objects. This is in contrast to a more classic TDD style that prefers to verify the code works by checking the state of an object after an interaction.  I wouldn’t claim to be an expert in the London School of TDD, but I think I understand the basics and can adopt this style when I feel the problem is appropriate for it.

I tried out Luca’s four problems, (here on github) to see how I did. Luca very kindly gave me some feedback on my code, and I found hadn’t done as well as I had hoped to in adhering to SOLID principles. I’d got the code under test, but in a few places I could have improved the design more. I also slightly misunderstood the requirements for two of the problems, which led me to fork the repo and improve the instructions 🙂

I think in the cases where I could have done better with the design, it’s possible using the London School of TDD would have led to the improvements. I’m feeling there might be something in Luca’s conjecture. On the other hand, these problems might be so small and abstract, that I didn’t behave the same as I would in a real codebase. Certainly in one case I felt it wasn’t worth extracting an interface when there was only one implementation for it. In a real system maybe it would be more obvious that more implementations were likely, and that adding the interface would lead to a more decoupled design. Or then again maybe I’m just too used to python where expicit interface classes don’t tend to be used. Or maybe I’m just making excuses! In any case, doing these exercises has made me more interested to improve my knowledge and practice of the London School TDD style. 

I think these exercises are interesting little code katas in their own right, quite apart from Luca’s study on TDD. I think you can use them to learn about the SOLID principles, and practice some of the refactorings you often have to do to get badly designed code under test.

I’m working on a python translation of the exercises so we can try them out at the Gothenburg Python User Group meeting next week. Feel free to fork the repo and have a go at them yourself.