Software that works.
In production.

A software consultancy in Stockholm helping teams ship better software using Test-Driven Development, Behaviour-Driven Development, Clean Code, and Continuous Delivery.

Continuously deploying to production for more than 15 years, underpinned by a thorough safety net of tests.

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Thoughts on testing, craftsmanship, and getting software into production.

2026-09-02

Characterization Tests: A Safety Net Before You Refactor Legacy Code

You want to refactor a class and the tests you were counting on are not there. Or they are there, but they aim somewhere else and none of them would notice if you got this particular piece wrong. The code works, presumably, since it has been in production for years. You just have no way to prove that it still works once you have touched it.

Characterization tests are for this situation. You write tests that describe what the code does right now, and then you refactor with those tests watching your back.

Coding assistant Software development TDD Test automation
2026-08-21

Migrating from Spark to Javalin: You Can't Strangle a Web Framework

Changing a web framework must be done the same way you would change an aircraft engine midair. You do it prudently, in small, safe steps all the way. You test everything so no surprise surface when you do the switch.

I moved LogEze to Javalin. It is a product I have built since 2014, and it ran on the Spark Java web framework until recently. The cutover was one environment variable. I flipped it and everything switched from Spark to Javalin at once. Most of the work was in the preparations. Two weeks of them were hands-on work, abstracting Spark away from the core of the app far enough that a parallel Javalin implementation could be built alongside it and switched on safely. The rest started a lot earlier, with spikes to settle on the replacement and a shared super class that every controller already ran through, in place more than two years before I needed it.

Java Software development Test automation
2026-07-01

A Revival for Test First, If We Don't Waste It

Using a coding assistant might turn out to be the best thing that has happened to Test-Driven Development (TDD) so far. This is the seventh post in my series about coding with an assistant.

For more than twenty years the objection to TDD was always some version of the same thing. No time. Too much typing. We will add the tests later. The assistant removes that objection. It types the test for you in seconds and it does not get bored doing it. On top of that, the path of least resistance with an assistant now runs straight through the test. I made that case in Fitness Functions for an AI Coding Assistant. To get useful work out of the assistant you have to tell it what done looks like, and a description of done that a machine can check is a test. TDD stops being the disciplined choice and becomes the efficient one.

AI BDD Coding assistant TDD
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Training

Hands-on courses on testing, automation, and getting software into production. All available upon request.

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Behaviour-Driven Development

Building shared understanding through conversations and concrete examples. 2 days.

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Test-Driven Development

Red, green, refactor. Testing as a design discipline, not an afterthought. 2 days.

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Web Testing with Selenium

Maintainable browser automation that catches regressions before your users do. 2 days.

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Web Testing with Playwright

Fast, reliable, cross-browser testing for modern web applications. 2 days.

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Specification-Driven Development with AI

BDD and TDD meet AI assistants. A renaissance for specifications. 2 days.

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Fullstack Testing

From React to database and back. Test every layer with confidence. 2 days.

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Continuous Deployment

From idea to production in hours. Build the pipeline and the discipline. 2 days.

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Testable Architecture

Hexagonal architecture. Easy to test, easy to change, easy to deploy. 1 day.

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Refactoring and Simple Design

The four rules of simple design. Safe, incremental improvements that pay off technical debt. 2 days.
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We speak about

Available for conference talks, meetups, and team workshops.

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Test-Driven Development

A pragmatic guide to writing tests first and letting them drive your design.

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Behaviour-Driven Development

It's not about the tools. Building shared understanding through examples.

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Continuous Integration

Ship with confidence. Automate your build, test, and deployment pipeline.

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Upcoming speaking engagements

2026-09-25
Presentation

After 25 Years of Test-First, I Started Pairing with an AI

Confitura, 2026 — Warsaw, Poland
2026-10-11
Presentation

After 25 Years of Test-First, I Started Pairing with an AI

JavaCro, 2026 — Rovinj, Croatia

Recent speaking engagements

2026-05-14
Presentation

Pairing with Claude: My Experience Using AI for Test-First Development

GeeCON Krakow, 2026 — Krakow, Poland
2024-10-22
Presentation

The four rules of simple design

JDD, 2024 — Krakow, Poland
2024-05-15
Presentation

Celebrating twenty years of The four rules of simple design

GeeCON Krakow, 2024 — Krakow, Poland
2023-10-19
Presentation

Let’s dive into the topic of testability

GeeCON Prague, 2023 — Prague, Czech
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