AI-Assisted Development Means Test-First Development

Jens Oliver Meiert, an engineering lead and web developer, argues that developers using AI must adopt a test-first approach, writing tests before implementing features or fixes to protect projects and keep AI work on track. He updated the post on August 22, 2026, to clarify that 'test first' is more accurate than 'test-driven development' after feedback from Ted M. Young and Benjamin Eskola.

AI-Assisted Development Means Test-First Development Published on Aug 20, 2026 updated Aug 22, 2026 , filed under development https://meiert.com/topics/development/ , ai https://meiert.com/topics/ai/ . Share this post https://shareopenly.org/share/?url=https://meiert.com/blog/ai-and-tests/&text=AI-Assisted%20Development%20Means%20Test-First%20Development , e.g., on Mastodon https://s2f.kytta.dev/?text=AI-Assisted%20Development%20Means%20Test-First%20Development,%20by%20%40j9t%40mas.to%3A%0A%0Ahttps://meiert.com/blog/ai-and-tests/ . If you’re developing using AI, you need to start from tests. If there’s one lesson I learned from developing, maintaining, and optimizing using all sorts of models—something I missed calling out in previous https://meiert.com/blog/ai-tips-for-web-developers/ tips https://meiert.com/blog/ai-tips/ —, then it’s this. Start from tests. The way you do this—and you may need to be explicit as I’ve seen many models slap on tests after the fact—is by asking to first write tests for what you create or fix—and then develop the feature or implement the fix . Rinse and repeat. Starting with tests protects your project: - You confirm that the respective feature is missing or broken and it’s recommended that you review and run the tests or, at least, take samples . - You put a guardrail in place so that any AI instance doesn’t veer off—any work it does should lead to developing or fixing the feature. - You confirm that the feature was indeed built or fixed. - It keeps yourself centered on the problem. Now, I’m frontend developer first, web developer second, programmer last, and therefore look at some processes from an off-position. Still, working with AI has proven to me the value of test-first development. If you’re working with AI, and aren’t a strong programmer, try starting with tests, too. While you will need to get used to testing, this is easier and safer than “just shipping.” Update August 22, 2026 The first version of this post linked the approach to test-driven development https://webglossary.info/terms/test-driven-development/ . Readers on Mastodon—thanks Ted M. Young https://ted.dev/ and Benjamin Eskola https://eskola.uk/ —pointed out that this would not be accurate, that “test first” would be more appropriate. I do understand there to be a connection between test-first and TDD, but with my background as mentioned, I appreciate the feedback—and hence updated the post. “Test first” does well match the spirit of what I learned to be effective. About Me I’m Jens long: Jens Oliver Meiert , and I’m an engineering lead, guerrilla philosopher, and indie publisher. I’ve worked as a technical lead and engineering manager at various companies e.g., Google ; I’m an active web and tool developer code optimization, digital defense , a contributor to web standards like HTML, CSS, WCAG , and a book author O’Reilly, Frontend Dogma . I love trying things—in web development https://meiert.com/topics/development/ and engineering management https://meiert.com/topics/management/ , but also in politics https://meiert.com/topics/politics/ and philosophy https://meiert.com/topics/philosophy/ , where I hold to one idea in particular: that we can only be well if we take good care of everyone. Here on meiert.com I talk about some of my perspectives and experiences. Interpret charitably https://en.wikipedia.org/wiki/Principle of charity but be critical—and share feedback and advice https://meiert.com/contact/ that makes my work better.