Takeaways from GeeCon Prague 2023

I recently attended GeeCon Prague, an event I had never been to before. While it wasn’t as grand as the big Krakow event, I still found it a worthwhile decision to attend. Here are some highlights and things that resonated with me:

What I Discovered and Deepened My Understanding On

  • Availability Bias: While I’ve always felt its presence, I now have a formal term and understanding of it.

  • The Big Rewrite Song by Dylan Beattie is a beautiful one:

  • There is evidence supporting my frequent claim that developers spend more time reading code than writing it. This is further discussed in the book ‘The Programmer’s Brain’.

    We spend more time reading code

  • There’s an insightful talk on How to Teach that isn’t exclusive to programmers. I found it enlightening and recommend it:

  • Interesting fact: Only 37% of code written five years ago is still in use today.

    Focus On New Code

  • The “First Glance” technique for reading code is intriguing. It involves group members sharing what stood out to them in the initial minute of reading a piece of code. I now want to try this in an ensemble setting.

  • You don’t really need anything other than Redis 🤣.

  • There is more to Pattern Matching than I had anticipated.

  • Java’s efficiency has notably improved.

    Java Efficiency Chart

  • On Crafting Better IDs: While UUIDs are reliable, they’re not the fastest. Creating a custom solution could be more efficient. UUIDs rely on secrandom, which is often unnecessary and slows down the process.

    XUID variations exist that maintain order. If you’re keen on using UTC, consider synchronizing time across services with NTP. A suggestion for EventIds: prefix them with the domain they originate from. To avoid potential issues, implement a processing count to ward off circular flows and employ tracingIds to streamline debugging in microservices.

Moments of Inspiration and Reflection

  • It felt good seeing Michael Feather’s Talk, as it provided me with a different perspective on trying to TDD with ChatGPT. Also, it was nice to exchange Ideas on the topic.

    TDD with GPT

  • Tannaz N. Roshandel highlighted the ethical challenges we face in a rapidly changing world in the digital age. I wholeheartedly agree. As we employ AI for sophisticated classification and recommendation, we amplify division. Can we harness AI to counteract this?

  • Overall, the technological landscape is constantly evolving and increasing in its complexity, overshadowing what is essential. To break the cycle of creating messes, we must shift our focus on the fundamentals. However, I’ve come to see that serverless might be a promising solution.

  • Meeting Bogo and heading to a pub with him to enjoy some excellent Czech beer was definitely a highlight! Thanks Bogo! 🍻

More Photos

Bogos Talk. No Time For Fun

He smashed his Phone 🤯 Bogo smashing his Phone

Michael Feathers proposed an idea on how to understand code using ChatGPT. An Idea how to use ChatGPT to read code

I had a nice view from the balcony of my hotel. View from hotel

Prague at Night. Prague at Night

Prague at Day. Prague at Day

to the comments

Solo Programming Considered Harmful

I was recently following an interesting discussion of the Vienna software crafts community with the title: “How to facilitate a conversation between people, where the byproduct is code?”. The discussion is in German and contains interesting ideas about how to code well together, and how to facilitate it. I tried to give an answer, which got longer and longer. In the end, I chose to write this blog post which expands upon the original topic of discussion and covers a broader range of related subjects.

I will continue to use the terms

  • coding together
  • collaborative coding
  • Mob Programming, and
  • Ensemble Programming

interchangeably. However, when I say coding together or collaborative coding this includes Pair Programming. When I say Mob Programming or Ensemble Programming I exclude Pair Programming. By the way: Yes, Mob Programming and Ensemble Programming mean the same thing and may be used interchangeably. It’s just that the word “Mob” might be associated with something negative, whereas “Ensemble” is a more innocent term. However, I like to use “Mob” as a verb because it’s so short and simple:

  • “Let’s mob on this problem!”
  • “We have been mobbing on this problem.”

Solo Programming Considered Harmful

Solo Programming » A programmer is a person sitting solo in front of their computer, typing rapidly on their keyboard. A well known stereotype. You have seen the movies.

It turns out that solo programming may not be as good as we think. No, I’m serious. I think we overestimate our programming skills. We tend to overcomplicate things, and we make a lot of mistakes. We rarely understand the problem that needs to be solved, and we don’t know our tools well. We often end up with crufty code that isn’t as simple as it could be. It doesn’t work and often targets the wrong problem.

But hey, don’t worry about it. We don’t mean to. We try hard to live up to expectations. And we work to the best of our ability. We’re learning. It’s just not that easy. 🤷‍♂️

Coding Together as an Answer

Collaborative coding can greatly improve the situation. By bringing together multiple people with different skills and perspectives, we can gain a deeper understanding of the problem and develop a better solution. We can take on different roles and complement each other. We have more eyes to spot mistakes, and together we know our tools better and know more about valuable techniques and practices. It’s proven that complex problems can be solved better and faster through collaborative coding. Working on simple applications, we encounter such hard-to-solve problems every day. But the best thing about coding together is the amplified learning while having a good time.

Remote Mob Programming » A team coding together remotely.

The Cost of Coding Together

There is a cost, of course, to having many programmers working on the same problem at the same time. We understand those costs well, I think. What we do not understand so well, however, are the benefits. Ultimately, it’s a tradeoff. Will the benefits outweigh the costs? So let us talk about the benefits.

The Benefits of Coding Together

Amplified Learning

The most striking advantage, and I cannot emphasise this enough, is the amplification in learning. We need to learn and get better at what we do, desperately so. All of us, but especially those of us who are new to it. There’s a big gap between what you learn in school and what you need to know on the job. We have to make up for that gap somehow. The thing that works best in my experience is to work together with the people. Coding together isn’t only the best way to onboard new people, but it also succeeds amazingly quickly in raising the level of participants and turning them into valuable contributors. I’ve learned so much myself through programming with other people that I honestly believe the learning effect alone makes up for the cost.

Reduction in Cost for Change

We are used to a trade-off between quality and cost, but it does not work that way with software. In our business, quality is cheap and cruft is expensive.

💡 Martin Fowler wrote an interesting article on this topic.

Code is a liability, and much of the cost is incurred when we need to change and improve it, which happens from day one. There is this strange idea that maintenance is something that happens after the project is completed. Well, that’s not exactly true. We maintain the code starting with the first day. It’s a challenge to find the right structure and keep it soft enough to change easily. It’s also terribly expensive to work on poorly designed legacy code, as we often see in enterprise software today. The cost of this is insidious because there is usually no awareness of it. So we should strive for and achieve high internal quality to save maintenance cost. The internal quality of the code can be greatly increased if many people review and revise the code as it’s written.

Better Software for the User

I have seen this repeatedly: Many minds working on the same problem produce more and better ideas, which simply leads to better solutions. When I say better, I usually mean simpler. It’s those moments when the majority chase a suboptimal solution and then one person proposes a better one. We need to think outside the box. Different people think in different boxes. More boxes mean more opportunities. More opportunities lead to a better outcome for the user.

Reduced Work in Progress

We know that high work in progress causes slow down. When we work together on one problem, it’s also the only problem we work on. All the people needed to solve the problem are there when they’re needed. And then, once we’ve taken all the necessary action, it’s done. It’s off the table. We can focus entirely on the next problem. No juggling of tasks. No waiting around. No context switching. Fewer things to keep everyone busy. Better and easier focus. A clean one-piece flow.

Having a Good Time

For many people, it can be rewarding to work in a mob with other people, especially if they’re more experienced. When working on software, we’re often thrown in at the deep end. Teamwork reduces the stress involved in this. It’s also more enjoyable for many. Coding together is a great team-building activity because we work as an actual team. It may feel awkward at first, but once you get the hang of it, it can be a lot of fun.

Mob Programming is Not Easy

Coding together is challenging. It’s not simply a matter of one person typing while others observe in silence. In order to make it work, it’s important for all team members to actively engage and collaborate. This enables us to utilize all of our minds and build the shared understanding we strive for. Also, we want to reach a flow state and make continuous progress. Mob Programming, thus working as an actual team, is a deliberate practice.

Shared Understanding

It’s important to ensure that everyone is on the same page and no one is left behind. This requires patience, effective communication, and a willingness to listen and explain ideas. Communication is a challenge, but a skill we can improve with practice. Speak slowly and use simple language. Use metaphors and pick people up where they are. When starting out with a new ensemble, it’s common to feel slow at first. This is normal as the ensemble gets to know each other and establishes a shared understanding. After some time you should experience a boost in productivity. The duration of this initial phase can vary, it could be as short as a few minutes or as long as an hour.

So, it’s all About Human Interaction

Treat each other with kindness, consideration and respect1. Make people feel safe to contribute, and welcome all forms of contribution, including questions. Reward a contribution, especially if it makes the person feel unsure. It is perfectly fine not to know something or not to “get it”. Be a hero and ask the first question to make others feel confident as well. Be open to examining and evaluating potentially disruptive ideas, even if they come up suddenly. Creating a supportive environment that encourages people to contribute will help ensure that the best ideas and insights from all team members are incorporated into the code. It seems like social skills are the name of the game. Has programming been the easy part all along?

Agree on a Shared Goal

With many different ideas being shared, it can be difficult for a team to agree on a common goal. This is another team skill to master. It’s important to be open to taking a step back and trying someone else’s idea. It’s okay to try multiple approaches and see which one works best. By being open to different ideas and perspectives, a team can learn and grow together.

Knowing when to Speak

It’s important for everyone to feel comfortable speaking their mind and sharing their ideas. However, it’s also important to know when to hold back and listen to others. One way to deal with this is to keep a private backlog of ideas that come to mind but may not be relevant at the moment. This can help keep you focused on the task at hand while recording and considering other ideas for later. Knowing when to speak up and when to hold back is an important skill for effective collaboration.

Bias to Action

In a group, it’s sometimes easy to get stuck in a discussion that goes on forever without trying anything. Most of the time, it’s less stressful to just try. Some discussions just are not worth it. If you notice people talking for several minutes without writing any code, alarm bells should be ringing. For example, if people are puzzling over the behavior of a particular code for an extended period of time. It’s time to call to action and suggest that you simply run the code and see.

Distributing Roles

A logical first step is to distribute participants by what they do. Someone has to type the code, of course. A common name for this role is Driver, as in the Driver/Navigator relationship of Strong Style Pairing. I often find that people confuse the names of these two roles, so I prefer to call them “Typist” and “Talker” instead. May also use “Typing” and “Talking”.

The Role of the Typist

We do not want the Typist to just hack away. If they did, other participants could merely descipher the then buggy code and make incorrect assumptions. That’s not sustainable. We want the Typist to follow the team’s instructions instead. Being a Typist is hard. They may get overwhelmed with conflicting ideas. What should they focus on? We can solve this problem by using a designated Talker. It’s not the only person who speaks, but they act as the primary input channel for the Typist, filtering all the ideas and making the final decision. Even if many things are said, the Typist then knows which voice to focus on.

A Typist Translates

It is a common misconception that the Typist foolishly types out the code they’ve been told to type, word by word, character by character. Actually, the Typist must make many considerations and decisions. For example: They may choose to run the tests whenever. They translate the Talker’s intention into code so that the Talker can stay at the level of their thinking. The Typist takes care of the details. That takes a big burden off the Talker. I mean, typing in itself is quite a challenge. To know your tools well and being good at typing is an art. If you are then able to translate the high level intent on top of that, that’s icing on the cake.

Typist Wrapups

One technique I learned at the Python Approvals Mob that improves feedback and shared understanding is Typist wrapups. It means that a Typist gives a brief explanation of what just happened and what they did after each round. When a Typist explains this in their own words, misunderstandings are more likely to be uncovered and cleared up.

Being a Talker is not Easy Either

So the Talker is the person who programmes. The Typist acts as a kind of intelligent input device for them. A Talker should communicate their thinking. In other words, they should think out loud. There are many stages of thinking that we go through. First, we orient ourselves to the current situation - the context. Second, we imagine where we want to go from here - a direction. Third, we formulate a concrete intention - still at a high level. This is already what a Typist could work with. Each thought step is shared with the team. Only then, if needed, do we move on to low-level details: What code to write on what line, syntax, code formatting, keys to use, buttons to click, etc. The Talker instructs the Typist at the level at which they can operate on, the higher, the better. Kind of like inverted limbo: How high can you get?

Contributing while not Talking nor Typing

Not being any of those roles doesn’t mean you’re not contributing. You may step out of the mob for a minute, but what you rather want is to be creative in supporting the group. Do some research when an opportunity arises. Ask, if you don’t understand something. Remind people about the protocol if necessary. Think ahead and take notes about things we should take care of. Review the code as it is being typed. Observe how the group behaves and what they are doing. Maybe you have an Idea of something the group should be trying that could work well, bring that up. Note down things that worked well so you can bring it up in the retro.


Everyone should get to type and talk. This keeps everybody engaged. When deciding on the rotation interval, consider how long it would take for the same person to become a Typist again. Waiting an hour to go back to typing is probably too much. It’s hard to maintain attention that long. A rotation every 2 or 3 minutes works very well with an experienced mob, but you need to be able to do it swiftly. Work hard to shorten your rotation time. Rotation time is the time between the start of a rotation and the next Typist/Talker being able to continue. The perfect rotation time is 0.

Rotations Need Trust

Ending your turn thus giving up control can be difficult. As a Talker, you not only want to maintain the direction of the previous Talker, but you must trust the next Talker to do the same. Trust them to continue the idea you have been working on. Without trust, rotations get bogged down, which hinders the flow.

Hard Rotations vs “Finish Your Thought”

When the timer sounds, you have the option to do a hard rotation, where work stops immediately and team members rotate positions. Another option is to take some time and finish your current thought, known as “Finish Your Thought” (FYT). FYT is useful for completing something small or finishing a line of code. However, when it takes too long, it can disrupt the flow of the team. People might forget or even ignore that the timer rang at all. Based on my experience, in those cases, it’s better to do a hard rotation. Trust in the next person to pick up where you left off and continue the team’s intent.

Calling out your Role

Another common practice that helps maintain flow is when everybody calls out their role when the rotation starts. It’s practical to also have the person that will be participating in the following rotation to call that out as being “next”. This avoids misunderstandings and it makes sure that the “next” person is increasing their attention towards being able and continue the given work.

An example would be:
Alice: “I’m Alice, and I’m talking!”
Peter: “I’m Peter, and I’m typing!”
Sarah: “I’m Sarah, and I’m next!”

Find out what Works for Your Mob

As mentioned earlier, Mob Programming is a deliberate practice. You want to constantly improve the way you work together. There are no pre-existing rules or frameworks for this. You need to find your own working agreements. Regular retrospectives are key in this regard. Conduct them at least daily. A two-hour Mob Programming session can lead to a three-hour retrospective, which is great. The learning effect can be tremendous. But they don’t have to be that long. Make them short, maybe a few minutes, but regular. Use them to find out what worked well for you, and put that in the spotlight. Turn up the good. Stay innovative and figure out what you’d like to try. Retrospectives are about learning and about change. Use it, act on its results.

Facilitating a Mob Programming

Above all, remind the participants to be patient and treat each other with kindness, consideration, and respect1. Be a role model in the way you treat them. People new to Mob Programming will be overwhelmed just by the conviviality of this way of working. Suddenly they have to pitch their ideas to other people. They are also not used to being exposed while typing code. It will take some time for them to get used to this way of working and still have some room in their head to keep a protocol intact. So you want the initial protocol to be minimalist, and you want to guide it. Too many rules would throw them off the rails.

Tip: When you notice someone being distracted, offer a short break.

Guide your Protocol

There is a fine line between telling everyone what to do all the time and letting them off the hook. In the beginning, they won’t remember how to follow your protocol. It’s just too much. So you should guide them and kindly tell them what to do and when. But you also don’t want to fall into the trap of doing everything for them. Your goal is for the team to be able to take care of themselves and for you to become redundant. Therefore, every time before you remind them, you should also give them some time to follow the protocol themselves. Once you become redundant, you may consider joining the mob.

Tip: Do not join a fresh ensemble as a facilitator unless you are very experienced in this. Facilitation can be complicated, therefor you do not want to particiate in the programming at first. Stay out of the ensemble and focus on having them work well together.

Keep Time for a Retrospective

You want to end a Mob Programming session with a retro. Give them the chance to express their feelings about what happened, and share it with each other. They probably enjoyed it. Also, they have probably learned new things in the progress.


A minimal but nice format for a retro is a microretro. It only takes a few minutes and you could do it at least once a day. In this retro, ask these questions:

  1. How did that feel?
  2. What worked well?

    The aim of this question is to highlight the positive aspects and achievements. We want to celebrate what went well and strive to replicate it in the future. It’s easy to get caught up in dwelling on negative aspects, but this can lead to a negative mindset and impact the overall well-being of the team. Therefore, this retro focuses on shifting the perspective entirely towards the positive.

  3. Do you have an idea you would like to try?

    The goal of this question is to foster experimentation and innovation.

Tools for Mob Programming

  • mob.sh is a commandline tool and git wrapper to easily hand over code in a remote mob programming.
  • mobti.me is an online mob timer, and the best that I know.
  • gitpod is a webapp that is basically vscode in the browser that works well for collaboration as you can share your workspace with others.
  • remdev on azure is a script to easily boot up a virtual machine on azure for remote mob programming.
  • cyber-dojo is a brilliant webapp to practice mob programming on a kata. All you need is a browser.
  • tmate allows you to share your terminal with others to collaborate.

Public Mobs

If you want to try Mob Programming you may choose an existing community.

  • MobRPG Mob is a weekly public remote mob on thursdays where we develop a webapp for the mob programming rpg. Read the Contribute section to find out how to join (It’s dead simple as in “just show up”).
  • Code Crafts Saturdays and Sundays is a monthly event where you can try and practice Mob Programming and TDD.
  • Python Approvals Mob is a weekly remote mob that works on the python version of the approvals testing library.
  • Mobus Operandi has a calendar with a lot of public mobs that you can join.
  1. Kindness, Consideration and Respect are what make a healthy Mob Programming.  2

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Getting better at CI

I recently felt the urge to experiment with my TDD workflow and improve it. It had too many manual steps, like running the tests, starting a commit, writing a commit message, pulling changes, and pushing it. It felt boring and wasteful. I want to automate this stuff and eliminate all the waste.

We’re not aiming high enough with the continuous part in CI/CD.
“Integrate at least daily” … Come on!
“Hourly” … We can do better than this.
“Short-lived Feature Branches” … You got to be kidding. It’s rather “short-lived lies”.
None of this is continuous. We need to get better and decrease the risk even further. I want to integrate actually continuously.

My inspiration comes mainly from the ideas of continuous integration, continuous testing, TCR, and limbo on the cheap.

Actually continuously

I came up with a way that drastically increased my commit frequency. I managed to create 63 commits in just 25 minutes practicing this way, where I peaked at 6 commits per minute. Yes, it was just a kata, but that’s not the important part. On many occasions literally every keystroke went live, and it was all working - covered by tests.

What I did is based on the following requirements:

  • No manual saving. The code saves itself automatically.
  • No manual test running. The tests run continuously. They restart automatically as soon as the code changes. And they are fast.
  • No manual commits. The code is committed automatically whenever the tests pass.
  • No manual pulling. Changes are pulled automatically before the tests run.
  • No manual pushing. Every commit is automatically pushed right away.

Not that hard to achieve actually. Just need proper tooling and a little bit of scripting. The language I’m trying this with is Java.

The right tools for the job

Since I use IntelliJ, which is a great, maybe the best IDE (*cough* it became a little buggy as of recent *cough*), it saves my code automatically. So that problem is already solved. For the continuous running of the tests, I know a few options.
IntelliJ offers a way to trigger the tests automatically, but it’s rather slow. Then there is this old-school plugin infinitest, but I need something for the CLI so I am able to script it. And it should be really fast. Incremental compilation would be key.
Gradle has it, and it is quite fast. With Gradle, I could also make the test report pretty using this test-logger plugin.

Nice test report with the gradle test logger

I like that!

Another option would be the quarkus continuous test runner, which is fairly new, and its test report is so ugly. Also, I have no idea how to customize, or script it. So I am going with Gradle for now.

On top of the incremental compilation, Gradle ships with a continuous test runner in:

> gradle -t test

But since I need more control I chose to use a little helper tool called watchexec instead. It watches for file changes and then executes a command. Like this:

> watchexec -e java ./gradlew test

I made some tests and it is just as fast as the Gradle continuous test runner. If you’d like even more control and a more complicated script, you could also use inotifywait. However, I like to keep it as simple as possible.

Next, I needed to commit as soon as the tests pass. A simple bash script would do, but I like to use a modern task runner for the job. I settled with just. In case you did not know, it is a modern version of Make. And it is written in rust for whoever that may concern. The way this works is you just create a justfile and specify your tasks in it. The commit command looks like this.

    @git add . 
    -@git commit -am "wip"

Simple and concise. To execute it you run:

> just commit

And I do not even have to remember. My shell courteously suggests to me the available commands.
The @ means that the command is not printed.
By default just would abort on an error exit code, whereas the - tells it to ignore that and continue. I need this for the case where the tests pass, but I have not changed anything. For example when I add something and delete it right away. Then there would be nothing to commit, and git would throw the error, having just abort the task. I could also allow the empty commit using the allow-empty flag. But why allow an empty commit for no reason!? That would be inventory, wasteful.

So here are the first commands in a justfile.

    @git add . 
    -@git commit -am "wip"
    @./gradlew test

    just test 
    just commit

    watchexec -e java just test-commit

Nice! I like it.

First Try

Now we are able to give it a try. Small steps.

  • Run > just tdd-commit in a terminal that stays visible next to the IDE.
  • Write a very simple failing test; Tests fail. -> The test failure is shown in the terminal immediately.
  • Make the test pass. -> Nicely formatted test report is shown immediately. Changes commit automatically.
  • Rename the test method; Tests pass. -> Changes commit automatically.
  • Add another test; Tests fail. -> I am shown the failure report.
  • In a first attempt to make it pass I notice I cannot make it as easily. I need a preparatory refactoring first.
  • So I disable the failing test; Tests pass again. -> Changes commit automatically.
  • I do the preparatory refactoring; Tests pass. -> Changes commit automatically.
  • I enable the failing test again; Tests fail. -> I am shown the failure report.
  • Make it pass this time; Tests pass. -> Changes commit automatically.

Wow, this felt smooth. During all of this, I had not manually done a single save, test run, or commit. The terminal was open on the right-hand side of my screen, and I got that feedback immediately, continuously.

A meaningless commit history

Let’s take a look at the resulting git history.

  • wip
  • wip
  • wip
  • wip
  • wip

Whoops, that’s not very expressive. But the commits are so small and pleasant to review. It’s like a playback of every little step that was taken. It is the actual history. Honestly, I think the flow might have more value than the documentation. Still, I would like to improve on that by sneaking in descriptive empty commits every once in a while.

We are used to writing git messages that describe what we did after we did it. But for this, I would like to propose a different way. I want to use a commit message to describe what is next. In other words: What my current goal is. So let’s add a command to create such descriptive empty commits.

goal +MESSAGE:
    git commit --allow-empty -m "Goal: {{MESSAGE}}"

Every time I start working on a new goal, I want to write it to my git history first. Something like > just goal make rover turn left. The other commit messages would stay ‘wip’ commits and that’s fine. One idea would be to use further tooling to decode some of the refactoring commits. For example: The refactoringinsight plugin.

My commit history would then look something like this:

  • wip
  • wip
  • wip
  • Goal: make rover turn left
  • wip
  • wip
  • wip
  • wip
  • Goal: make rover turn right

But what about Integration?

Lots of small commits on my computer are nice. But if I work in a team I need to integrate my changes to the mainline, too. So I want to pull before I run my tests, and I want to push after each commit. It’s called Continuous Integration for a reason, right?

Let’s add that to the justfile.

    git pull --rebase
    just test    
    just commit  
    git push

And I think we’re done.

This is the complete file. It also contains a TCR task.

goal +MESSAGE:
    git pull --rebase
    git commit --allow-empty -m "Goal: {{MESSAGE}}"
    git push

    @git add . 
    -@git commit -am "wip"

    @./gradlew test
    git pull --rebase
    just test 
    just commit
    git push
    watchexec -e java just test

    watchexec -e java just integrate

    @git reset --hard &> /dev/null
    @git clean -df &> /dev/null
    @echo -e "\033[0;31m=== REVERTED ==="
    @just test && just commit || just revert


Notice how I renamed the tdd-commit task to ci. Continuous Integration is not only about what the build server is doing, it is primarily about what we do.

Coding with this script feels super smooth. It is actually continuous.

Also, it was not that complicated to set up. You can probably do even better.

Imagine remote pair- or mob programming with this. Hand-overs could not be easier. You just exchange the screen-sharing while the tests pass. And that’s it.

Probably some people are already working this way? Let me know!

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Running a Company Coding Dojo

Two years ago, in 2019, I ran the first Coding Dojo at my company EBCONT. Corona wasn’t a thing back then, so it happened to be an offline event that lasted 4 hours on a Thursday afternoon. All the brilliant people came together to practice programming and enjoyed it. How awesome is that?

Local Coding Dojo at EBCONT

A lot has changed since then. When the pandemic happened, I had to adapt and move it online. So I decided to make it a regular remote whole-day event. Luckily I had already collected plenty of experience from my friends at the Vienna Software Crafts Community where we also run Coderetreats.

The EBCONT Coding Dojo turned out to be a small success story. When I started it, I had approximately ten people join, many of which became regular attendees. But lately, there was a small hype around the event. People liked it so much that they came up with the idea to create a Coding Dojo T-Shirt and shoot a group photo with it. Of course, we did so. I had 25 employees join in the latest event, and it was a lot of fun.

Local Coding Dojo at EBCONT

Again, take a closer look at these sweet t-shirts! :-)

EBCONT Coding Dojo T-Shirts

Coding Dojo???

So what is a Coding Dojo, how do I do it, and what can you take away from my experience? The term Dojo originates in Japan and stands for a training facility where they perform katas, choreographed patterns of martial art movements designed for practice.

A Coding Dojo is a similar thing. We just perform coding katas. It is a great opportunity to practice technical skills like TDD, design, and refactoring. Invaluable fundamentals that are mostly not taught in school. They are left behind the things that turn out to have higher demand: Frameworks and tools.

Under pressure, we naturally fall back to old and maybe poor habits, even though it leads to worse results. So we take our time to practice and get comfortable with better programming techniques and to be confident to apply them when it counts. While the traditional Coding Dojo is a short ~2-hour event, the one I do lasts almost a whole day.

The Coding Dojo creates space for developers to practice the fundamentals of programming, away from the pressure of getting things done.

But why not a full day?

An intense full-day practice event can become tiring in my experience. Closing just a little bit sooner leaves everybody more energy for the final retrospective and the evening after the event. There are similar whole-day events in the name of Coderetreat and Mobretreat. The classical Coderetreat has the notion of throwing away your code after a timeboxed session and starting from scratch with a different pair. So you don’t finish, but get to see many different perspectives within a short time - quite intense. That’s a little different from what I do. I like to provide the participants the opportunity to dive deeper into a kata. So we stay within the same teams and kata throughout the day. This reduces the relative amount of setup time, which allows us to get more coding done.

The Dojo plan

I decide on the topic and kata in advance, taking the attendees’ skill levels into account. Before the event, I send them information about what we’ll be working on. The Dojo starts with a short welcome where we have a few minutes of small talk before the intro session begins. In the intro session, we discuss the topic and kata. I like to walk over a minimum of the theory that I believe everybody should know. One effective way to do this is to keep asking questions so they provide the answers themselves. At the end of the intro session, we form the teams whose be working together in the following coding sessions.

Balancing teams

I want less experienced people to learn from more experienced people. But that doesn’t mean more experienced ones won’t learn. They deepen their understanding as they communicate their ideas. Curious participants may even challenge their thinking and help them to refresh or even reset. So I like to balance the skill levels among the teams while also taking into account their desired programming language. The tool I use Gather-Town helps me with that.

Gather-Town is a remote video conference tool that works like a multiplayer version of Zelda. You can move around on a 2d map and talk to people in your vicinity. It creates that feeling of meeting somebody at a conference in the hallway again, just online. And it allows us to split up and go to different rooms. Also, it gives me the freedom to customize the map. I use an altered version of a map that Christian Haas once made for Viennas Global Day of Coderetreat.

I ask the people to assess their abilities and to take a position in the room that matches their confidence to work on the given kata. Standing on the right end of the room means “very confident” and the left end means “I’m lost”. The rest of the spectrum is in between. This creates an overview that makes it fairly easy to form balanced teams. In my opinion, the optimal team size is 3, but 4 works too. For bigger teams, you might want to assign a designated facilitator.

Tip: Assign a facilitator for a team

It is not possible for me as a single person to facilitate the programming in every team. Especially when the people are not used to collaborative coding it makes sense to assign a designated facilitator. The responsibility of this person is to provide just enough guidance for the team to work well together. This can be anyone who knows a bit of mob programming. The role can be rotated so that everybody gets the chance to contribute. When the team is small and most people are already used to this, a facilitator might not be necessary.

Coding sessions & retrospectives

Typically we manage to have three coding sessions, each of which is followed by a short retrospective. In these retros, we discuss anything interesting. How we feel, what we discovered and learned, and how we approached the exercise. We might also share and review the code we had written so far.

The first session always includes setup, which is the time spent until the team starts coding together in some way. Somehow, setup always takes a fair amount of time - regardless of how well prepared you are. The goal is to minimize this time and maximize coding time. There are lots of ways to code together quickly, and you probably already have some in mind. However, I would like to share some ways with you I found work well.

#1 Single Driver Mode

A way to get to code quickly is to have just a single person who already has a setup prepared to share their screen. The downside of this is the risk of other people falling behind due to inactivity. The avoid that, the person sharing should behave as a passive driver while the other people make decisions and rotate the navigator role. I prefer when everybody gets to drive, but this usually takes more setup time.

#2 Cyber-Dojo

Cyber-Dojo.org works well for TDD katas, as it allows you to create and share a browser-based setup for any language in no time. However, it won’t provide you with all the conveniences your IDE does. Things like continuous compilation, autocompletion, automated refactoring, and so on are not available.

#3 Virtual dev environment

Another way to get to code together quickly is to join the same virtual development environment. It could be a virtual machine running in the cloud where everything is already set up. People would connect to it through some remote desktop software. I prepared something like this, where I can spawn an immutable Linux dev system on Azure: Remdev on Azure

A typical schedule

This is what my typical schedule would look like:

  • 08:50 - 09:10 - Welcome
  • 09:10 - 09:40 - Theory, Details
  • 09:40 - 10:50 - First Coding Session
  • 10:50 - 11:00 - Short Break
  • 11:00 - 12:30 - Second Coding Session
  • 12:30 - 13:30 - Lunch Break
  • 13:30 - 14:50 - Third Coding Session
  • 14:50 - 15:30 - Retro

Coding sessions already include 10-20 minutes of retro time. While it’s not a big deal to be a little late in the schedule, I want to nail the 1-hour lunch break. This allows people to plan and spend that time with their families.

My role as a facilitator

As a facilitator, I am not there to actively perform katas. Instead, my job is to make sure that every participant gets the chance to learn and practice. So I am merely the organizer and enabler. I watch out that we keep the schedule (which I’m terrible at) and mostly try to get out of the peoples’ way. Also, I’m there to help the participants when they get stuck or have questions. But this doesn’t mean I’m not learning. Quite the opposite is true. I learn a lot as I get to see amazing ideas, experience new tech, observe sociotechnical patterns, discover and rediscover non-obvious details.

During the coding sessions, I switch from team to team and observe what they’re up to. This works well with Gather-Town as I can literally walk from room to room. Occasionally I see things I am concerned with and bring that up. I try to do this by asking questions, sparking their creativity, and having them come up with their own solutions. Or I may see something interesting, for example, a pattern emerge that I find worthy of a discussion, so everybody understands. If you want to learn more about facilitation in this regard I recommend Peters Coderetreat-Facilitation Podcast. Many of the things I’m doing are things I learned from him.

Choosing a kata/topic

The Coding Dojo should be a place to practice the fundamentals. The perfect kata is not too hard for the attendees to tackle, is small enough to finish within the event, and is one that you as a facilitator already know well. But it doesn’t have to be perfect. As a refactoring exercise, I like the Expense Report Kata which is nice and small. Or the Order Dispatch Kata which is about Tell don’t ask. As for TDD katas I liked Snake, Game of Life, or Mars Rover. But I also did completely different things. For example, the Elephant Carpaccio Exercise which is about vertical story slicing and iteration.

Selling your Coding Dojo

If you want to start a Coding Dojo at your company, let me tell you that I think that’s awesome! I’d recommend getting your boss to agree that it will happen during the work-day and that it will be considered work-time. Missing know-how is a bottleneck in our industry, where the majority have less than five years of experience. Fresh developers have to learn so many things about their tech, tools, and frameworks these days, that there is little room left for programming fundamentals like TDD and refactoring. Some of those are mostly not taught in school either. When people get to practice these, they become better programmers. They get better at writing code that works, is more maintainable, and more secure, in less time. What boss wouldn’t want that?


The Coding Dojo is a great and fun way to provide developers with the space they need to get better at their job. People enjoy learning from one another in a relaxed environment like this. I’m proud of the progress participants have made so far at my Dojo. Feel free to contact me if you have questions, or if you would like to start a similar event. And if you already have something like this at your company, I would love to hear about that, too.

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TDD Crash Course from the BACK of the Room

I was recently giving a 2 hour TDD crash course remotely for a group of 5 people, and I find it worked out wonderfully! So I would like to share with you how I did it.

If you were searching for TDD guidance, this is not it! It is rather a guide on how to run a TDD crash course.

I recently read the book Training from the BACK of the Room!, which resonated with me, and it inspired how I ran the course. The book is highly innovative and turns traditional training upside down. The emphasis is on learners being active and talking more during the training instead of the teacher.

The Training Plan


The goal of this training is for participants to understand TDD and be able to practice the red-green-refactor cycle themselves. It is not a goal of this training to make TDD pros that can test drive their whole projects. While TDD is easy to start with, it is also hard to master. To get better, learners will need much more hands-on practice after the training. The course should provide participants with a smooth start on their learning journey.


I did it remotely. However, I don’t see a reason why it would not work in the same way locally.

Group Size

5-6 Participants.


Knowing the principles I used for this training will help you understand the reasoning behind its design.

  • Just show up. Coding sessions often require technical preparations for participants in advance. When the training starts, you somehow lose those 25 minutes to fix the issues every time. Two hours is not enough time for having this kind of technical troubleshooting. So for this training, there is no preparation for participants needed. All participants have to do is to show up.

  • Focus on the need to knows. TDD is a broad topic, but the essentials are few. Teaching everything from history to styles, test doubles, and so on would merely confuse the learners. So in this training, we focus only on the essentials.

  • Learning by doing. The training will have the participants experience TDD in practice, which is very important. We could explain what a baby step is and what the value of a fast test suite is. Still, learners won’t understand unless they experience it themselves.

  • Have learners talk the most. In traditional training, the trainer talks more than 70% of the time, which doesn’t help learners learn. Participants learn much more effectively when they are the ones talking. So this training aims at maximizing the amount of time that learners talk instead of the trainer.

  • Keep everybody engaged from start to finish. No participant should be listening passively for more than 10 minutes at a time. We want to keep them engaged to get the most out of their training.

  • The 10-minute rule. The 10-minute rule helps us to optimize for the approximate attention span of people. TV has conditioned us to receive information in small segments of ~10 minutes in length. After 10 to 20 minutes, learning begins to diminish. So we want to avoid dry instruction that lasts longer than that.

  • Psychological safety. Create an environment where participants feel comfortable to express their opinions without the fear of being wrong. We don’t want them to be afraid of making mistakes, so we don’t punish those. Instead, reward every form of contribution from the very beginning. Whatever learners have to say: Unless it’s not abusive, it’s not wrong - it’s interesting.


Two hours is not a lot of time. If the group already knows each other, we want to jump right into the topic. When that’s not the case, give them at least the opportunity to introduce themselves in a minute or two. I like to use one of the following Start-Up activities.

Start-Up Activity: Web Hunt (20-30 minutes)

Start with a “Web Hunt” activity where learners have 10 minutes to search the web and find three facts and come up with one question they have about TDD. Prepare a virtual board where the learners can put and share their findings.

Then, take another ~10 minutes to review the facts and questions they had put on the board. Have the participants present them, and try to stay out of the discussion as much as possible. When you are not satisfied with one of the facts, ask the other participants what they think about it. Try to have the learners answer all the questions on the board. If you have some great answers that you can back up with quality content such as links to blog posts, articles, talks, or books - that’s awesome. Add those in the end.

Keep in mind that it’s not about us (the trainers). It’s about the learners.

Alternative Start-Up Activity: What do you already know? (20-30 minutes)

Give learners 10 minutes to think of three facts they already know about TDD and have them put those on a virtual board for everybody to see. Then, take another ~10 minutes to have participants present the facts they had put on the board. When you are not satisfied with one of the facts, ask the other participants what they think about it. This activity connects learners to the things they already know. Typically, developers have already heard at least something about the topic. When they connect to these things first, it will help them evaluate what they had learned in the training.

Theory (10 minutes)

After that comes the only part of the training that is dry instruction. Take ten quick minutes to explain the essentials of the TDD workflow. The three rules of TDD provide a good start, but you probably want to explain the whole workflow. This wiki page gives a nice overview of all the steps involved.

Short Break (10 minutes)

At this point, we are typically 30-40 minutes into the training, and it’s an opportunity to have a 10-minute break. After that, continue with the practical coding part.

Practical FizzBuzz (60 minutes)

The kata I choose for this exercise is FizzBuzz, as it is pretty simple and can be completed within the available time. It should help with creating the feeling of having accomplished something which makes the learning stick longer. Also, we don’t want to confuse learners with a design challenge. That’s not the focus here. The focus is on the TDD workflow and the thought process and decision-making behind it. A bit of sugar on top is the opportunity to use a parameterized test, which learners often find interesting. The kata is being worked on in a special mob where everybody is assigned a specific role.

Roles: Red / Green / Blue / Navigator

As we like to keep all participants engaged, we assign each a responsibility that requires them to stay focused. Choose three people and assign them one of these referee roles:

  • Red Referee: This role is responsible to make sure we watch each test fail and that the error presented is useful and expressive.
  • Green Referee: Watches out that we only write the simplest code to fulfill the test, but not the line of code we know we’d need to write.
  • Refactor Referee: Makes sure we always refactor in the green and only in the green.

The other participants are navigating collaboratively. Take a look at strong style pairing to understand the Driver/Navigator relationship.

After half-time, ask your participants whether they would like to rotate their roles.

The Trainer is the Driver

The trainer is the Driver/Typist. Writing down test cases is another important exercise for learners, but it is not the focus of this training. The focus of this training is to have learners grok the workflow of TDD. To learn the decisions we make, when we have tests drive our design in tiny steps. And to achieve that, we would like to remove all other impediments. So the trainer plays the smart input device that makes it easy for the learners to write the tests they want. As a driver, the trainer is also able to step in and take control if needed.

The trainer shares their screen, test setup prepared with the FizzBuzz requirements as a comment on the dummy test, font size increased, and test result visible. Remember, the goal of the trainer is to stay in the background as much as possible. She might chime in to get things going but mostly asks the right questions and delegates control to the participants.

As a trainer, you might say: “I only type when you navigators tell me to.”, or: “What would be an even simpler test case to start with?” When you see something you are not satisfied with, play the ball to the responsible referee: “Green referee, what do you have to say about this?”, “Refactor referee, Is it okay that we do this refactoring now?”

Instruct participants to have their mics on! Sometimes people turn their mics off when they are in video calls which could be harmful in this training. When everybody is starring at the code, we won’t notice when somebody starts talking with their mic off.

Retrospective (10-20 minutes)

Find out what the participants have learned that they hadn’t known before. How did they feel doing FizzBuzz using TDD? Was there anything they didn’t like? Ask the participants whether they would want to apply it in their real projects and how. They are more likely to do so, when they commit to it publicly.


It’s astonishing how much you can still teach after getting out of the way. Of course, the crash course is just the start for the learners. It will provide them with the prerequisites to have more hands-on practice. After the training, they should feel more comfortable joining a dojo/code retreat.

Did you like the training design? Which parts did you not like? How are you teaching TDD? Leave me a comment.

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