Software Development, Testing & Open Source

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April 15, 2026

Everything we have

In a world with endless possibilities for code to be wrong, one approach alone is not enough to make our software truly robust.

The image shows an abstract, futuristic design with a dominant, glowing question mark as its central motif. It emerges from a chaotic, undulating landscape of geometric pixels and voxel-like structures in intense shades of pink, purple and blue. These create depth and dynamism. The chaotic background resembles a seething, digital terrain that symbolises disorder and complexity. The question mark rises stably and questioningly from it – perfect as a visual mood for fuzz testing, where random chaos reveals security.

April 8, 2026

Security through chaos

This practical deep dive into the philosophy behind "security through chaos" shows that security does not come from perfect foresight, but from surviving chaos.

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April 1, 2026

Beyond Best Practices

Testing, code reviews and documentation are all essential prerequisites that constrain the autonomy of AI, thereby safeguarding human agency in software development.

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March 25, 2026

Effective Code Reviews

Pair, pull, or post-push? Find the code review strategy that is right for your team.

A road disappearing into thick fog. A symbol of how AI-generated code may look readable and plausible to us, but we cannot tell whether it will lead us to the right destination.

March 18, 2026

Faster than understanding

An AI coding agent implemented a complex software metric in 15 minutes. I have now spent hours trying to figure out whether the implementation is correct. Is this really a productivity boost?

Glass sphere resting on wet pebbles at the shoreline, reflecting a pier and sunset, symbolizing a shift in perspective and bringing clarity to complex testing practices.

March 11, 2026

From anti-pattern to clarity

The any() matcher is deprecated. But migration is easier than you think – and leads to better tests.

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March 4, 2026

Better than withConsecutive()

I explain how PHPUnit 13's parameter set matchers finally solve the problem that made upgrading to PHPUnit 10 such a challenge.

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February 25, 2026

Replay Testing

Replay Testing leverages the memory of your event sourcing system to test new versions with real history and shows which oracles truly inspire confidence in your changes.

The image illustrates that valuable insights can be gained from recorded events through skilful processing and analysis, a metaphor for the value of event sourcing and automated testing in software development.

February 20, 2026

From Events to Insights

Event Storming, DDD, CQRS, and Event Sourcing are intertwined: the tests not only check the events, but also become living documentation and a bridge between technical expertise and code.

February 11, 2026

How my understanding of software changed

A classic database only stores the "now" and forgets history. In this article, I describe my journey to DDD and event sourcing and explain why we need to learn to model time itself.

February 4, 2026

Data Provider or Properties?

One test, hundreds of inputs, and an automatic edge case search. But property-based testing has a hidden pitfall that many overlook.

The image shows a hand against a dark background, presenting a glowing light form that is drawn half like a brain, half like a light bulb. The scene conveys focused clarity and symbolises small inputs with great insight – fitting for shrinking in property-based testing.

January 28, 2026

Smaller input, greater insight

Shrinking is the unsung hero of property-based testing. I show you how it helps to make inevitable errors understandable.

January 21, 2026

Property-Based Testing

We only test what we think of. That is precisely what can become a problem.

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January 18, 2026

Open Source, Open Feeds: Mastodon and PeerTube as online spaces for the PHP community

With phpc.social and phpc.tv, the PHP community is building its own donation-funded online spaces in the Fediverse – free from algorithms and fascist tech bros.

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January 14, 2026

Type-Safe Collections

Does PHP really need generics? A controversial thesis with a practical solution.

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January 7, 2026

How PHP and its ecosystem test each other

PHP tests Laravel, Symfony, PHPUnit, and more every night. PHPUnit tests PHP. This is Open Source collaboration at work.

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December 31, 2025

The Stub/Mock Intervention

Self-sabotaging mock objects? With PHPUnit 12.5, that's a thing of the past because the test runner now asks the right question: Do you really need a mock object, or would a test stub suffice?

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December 24, 2025

A festive break

I take a break from my weekly articles and invite you to a free online event where I will present the latest improvements to PHPUnit.

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December 17, 2025

A flight recorder for your code

Your PHP project has no tests and an upgrade is pending? The classic dilemma: to introduce tests, you have to change code – to change code, you need tests. How can you break this cycle? With characterisation tests.

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December 10, 2025

Seeing the Truth: Test Oracles

Your tests are successful. But are they really? Without a suitable test oracle, you will never know.

This image illustrates the contrast between technical motivation, represented by flowing, dynamic data streams, and domain motivation, represented by solid, stable foundational concepts. This visual metaphor illustrates the main point that DTOs facilitate the movement of data between layers, while value objects represent unchangeable domain concepts that form the basis of business logic. The layered architecture also illustrates how these objects are used in different contexts: technical boundaries versus core business logic. It emphasises the stability and predictability that immutability brings to testing practices.

December 3, 2025

Testing with DTOs and Value Objects

Know the differences between data transfer objects and value objects and understand why immutability helps with testing.

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November 28, 2025

Testing with(out) dependencies

Why distinguishing between test stubs and mock objects in PHPUnit significantly improves the quality and readability of tests.

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November 19, 2025

Path Coverage or Mutation Testing?

How thoroughly do your tests cover the code, and how reliably do they detect real errors? I show you how to find out.

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November 11, 2025

Open Source Blackout

Are you prepared for a world in which your projects freeze, deployments stall, and tech giants can no longer rely on free community-run infrastructure?

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November 5, 2025

More control, less friction: What's new in PHPUnit 12.4?

Discover how PHPUnit 12.4 helps you get there with less friction and more insight.

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October 29, 2025

Modern PHP Development

Modern PHP development combines proven principles with the latest tools. It brings together documentation, quality, automation, and AI.

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October 22, 2025

A look ahead to 2035

I discuss key issues for the future relating to ethics, digital sovereignty, Open Source, and web standards.

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October 15, 2025

PHPUnit features that surprise even professionals

Discover the hidden capabilities of PHPUnit and learn how to get the most out of your tests with clever features.

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October 7, 2025

From AmigaBASIC to AI

A personal journey from my first lines of BASIC on the Amiga to the question of how AI will shape the next generation of developers.

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September 1, 2025

Innovation through collaboration: The highlights of PHPUnit 12.3

Discover how collaboration with real-world developers has shaped the latest advancements in PHPUnit 12.3.

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June 16, 2025

Psalm or PHPStan?

Psalm or PHPStan: which tool is the better choice for code analysis? Or is it worth combining both tools for maximum code quality?

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June 8, 2025

30 Years of PHP, 25 Years of PHPUnit

I look back on 30 years of open source innovations.

Collaborative prioritisation of quality goals with LASR

May 10, 2025

ComoCamp 2025

I am thrilled by the inspiring workshops, exciting open space sessions and the uniquely open, collaborative atmosphere of ComoCamp.

August 25, 2024

SoCraTes 2024

SoCraTes has enriched and motivated me in a lasting way through inspiring discussions, exciting sessions on topics such as PHP, software testing, security and open-source funding, as well as the special, collaborative atmosphere.

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June 25, 2024

PHP_CodeSniffer or PHP-CS-Fixer?

Should PHP_CodeSniffer or PHP-CS-Fixer be used to get code "in shape"? Should both tools even be used together?

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March 22, 2024

PCOV or Xdebug?

Should you use PCOV or Xdebug to collect code coverage data? I give a personal answer.

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March 11, 2024

PHPUnit Code Sprint: March 2024

I recollect my experience at the PHPUnit project's most recent code sprint.

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November 28, 2022

PHP 7: Security Support Ends. Now what?

Security support for PHP 7 has ended. What does this mean for you?

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April 4, 2022

How I manage test fixture

I reflect on why I no longer write setUp() methods.

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August 2, 2021

Ready Or Not, Here It Comes

Is your software ready for PHP 8.1? Now is the time to find out.

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April 21, 2021

Do not mock what you do not own

If you use abstractions you don't own, testing may be difficult.

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October 8, 2020

Caching makes everything faster. Right?

While working on PHPUnit, I encountered an interesting problem.

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July 6, 2020

Failing IT Projects

I explain how we can learn from failed IT projects.

The image shows an analogue wall clock with a yellow frame hanging on a white wall. The time is approximately 6:50 p.m. The clock face has a simple design and the background of the clock and the wall are white, giving the image a very minimalist look. There is a lot of empty space on the left, while the clock is located on the right side of the image.

June 5, 2020

Who wound the clock?

I explain why PHPUnit no longer looks at the clock.

The image shows a wooden sign with the word "CLOSED" written on it. The sign is photographed at an angle and, thanks to its warm, brownish colouring, blurriness and strong grain, has a particularly atmospheric and nostalgic feel. It is reminiscent of a photograph taken in a small, cosy shop or café at closing time.

February 21, 2020

PHPUnit: A Security Risk?

The long story of a security problem that should not have been one.

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February 7, 2020

Migrating to PHPUnit 9

In the tension between backward compatibility and progress, a good developer experience must not be neglected.

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February 1, 2019

Blast from the Past

Package managers are worthwhile targets, even if no one uses them anymore. Background information on the breach of the PEAR infrastructure of the PHP project.