惯性聚合 高效追踪和阅读你感兴趣的博客、新闻、科技资讯
阅读原文 在惯性聚合中打开

推荐订阅源

D
DataBreaches.Net
钛媒体:引领未来商业与生活新知
钛媒体:引领未来商业与生活新知
云风的 BLOG
云风的 BLOG
B
Blog
博客园 - Franky
I
InfoQ
A
About on SuperTechFans
博客园_首页
L
LangChain Blog
量子位
腾讯CDC
Microsoft Security Blog
Microsoft Security Blog
博客园 - 【当耐特】
美团技术团队
V
V2EX
Apple Machine Learning Research
Apple Machine Learning Research
雷峰网
雷峰网
MongoDB | Blog
MongoDB | Blog
Microsoft Azure Blog
Microsoft Azure Blog
月光博客
月光博客
T
The Blog of Author Tim Ferriss
P
Proofpoint News Feed
G
Google Developers Blog
Last Week in AI
Last Week in AI

DEV Community

Authentication Security Deep Dive: From Brute Force to Salted Hashing (With Java Examples) Why AI Systems Don’t Fail — They Drift Spilling beans for how i learn for exam😁"Reinforcement Learning Cheat Sheet" I Replaced Chrome with Safari for AI Browser Automation. Here's What Broke (and What Finally Worked) How Python Borrows Other People's Work The $40 Architecture: Processing 1 Billion API Requests with 99.99% Uptime Vibe Coding: A Workflow Guide (From Zero to SaaS) Most webhook security guides protect the wrong side. The scary part is delivery. Headless CMS for TanStack Start: Build a Blog with Cosmic EU Age Verification App "Hacked in 2 Minutes" — What Actually Happened Comfy Cloud’s delete function does not actually remove files Running AI Models on GPU Cloud Servers: A Beginner Guide Event-driven media intelligence with AWS Step Functions and Bedrock I scored 500 AI prompts across 8 quality dimensions — here's what broke How to Call Google Gemini API from Next.js (Free Tier, No Backend Needed) The Portal Protocol: Reclaiming Human Connection in the Age of AI How to Fix Your Team's Scattered Knowledge Problem With a Self-Hosted Forum Intro to tc Cloud Functors: A Graph-First Mental Model for the Modern Cloud Designing Multi-Tenant Backends With Both Ownership and Team Access I Built a Neumorphic CSS Library with 77+ Components — Here's What I Learned PostgreSQL Performance Optimization: Why Connection Pooling Is Critical at Scale Cómo construí un SaaS multi-rubro para gestionar expensas en Argentina con FastAPI + Vue 3 🚀 I Built an Ethical Hacking Scanner Tool – Open Source Project I Replaced /usage and /context in Claude Code With a Single Statusline A Pythonic Way to Handle Emails (IMAP/SMTP) with Auto-Discovery and AI-Ready Design I Collected 8.9 Million Polymarket Price Points — Here's What I Found About How Markets Really Move EcoTrack AI — Carbon Footprint Tracker & Dashboard Everyone's Using AI. No One Agrees How. 5 self-hosted ebook managers worth trying in 2026 Building Your First AI Agent with LangChain: From Chatbot to Autonomous Assistant
AI Coding Agents Need Tests More Than Prompts
Stephan Petzl · 2026-06-25 · via DEV Community

Over the last eight months, my software development workflow has changed more than I have ever experienced before.

And I say that as someone who has been writing software for about 25 years. I have worked through plenty of programming languages, frameworks, architectural fashions, build tools, frontend revolutions, mobile platform quirks, and enough JavaScript ecosystem churn to qualify for emotional compensation.

For a some time, AI coding tools were helpful, but only in a limited way. They were great for small tasks. Rename this. Refactor that. Write a helper function. Explain this cryptic error message that looks like it was generated by an angry toaster.

But building larger features with AI? Painful. GPT-4 at that time did not convince me that my job would be taken over by a robot. Not at all.

Working with GPT-5.1 still often felt like working with a brilliant intern who had read the entire internet but kept misplacing their notebook every 10 minutes. Once important information fell out of the context window, the AI would forget what we had agreed on and confidently wander into the bushes. Around late 2025, first with GPT-5.2 (and also Claude Sonnet 4.5) and then much more noticeably with GPT-5.3, AI coding finally became genuinely productive for me.

Small tasks? Excellent.

Longer tasks with several iterations, corrections, architectural context, and dependencies across multiple files? Kind of working!

And because of that, my role has gradually shifted from “person typing code” to “person designing the environment in which an AI agent can safely type code without setting the kitchen on fire.”

AI Agents Are Getting Better — But GUIs Are Still Their Swamp Level

Modern coding agents are now surprisingly good at a very specific loop:

  1. Read code.
  2. Change code.
  3. Run a command.
  4. See what failed.
  5. Fix it.
  6. Repeat until things look less terrible.

This is powerful.

But there is still one area where they struggle: graphical user interfaces.

AI agents are not yet great at reliably clicking through a UI, visually understanding what happened, and deciding whether the behavior is correct. They can try, but it often feels like watching someone test your app through a foggy bathroom mirror.

So I changed my workflow.

Whenever possible, I now build new features so they can first be exercised from the command line.

For small features, this can be a unit test.

For larger features, it can be a small standalone client or command-line program that runs the new functionality independently of the actual UI.

The important part is this: the agent needs something it can execute directly.

Not “please look at this screen and tell me if it feels right.”

More like:

npm run test:feature-x

or:

node scripts/run-new-feature-client.js

That is where agents shine. They like commands A LOT. Commands are their little ice skates.

My Current Workflow

The workflow I use today looks roughly like this:

  1. Plan the feature in a Markdown file.
  2. Create a test client, unit test, or command-line entry point.
  3. Define meaningful test cases.
  4. Let the agent implement the feature.
  5. Let the agent run tests repeatedly.
  6. Review the result carefully, because agents are clever little gremlins.

The Markdown planning step is important. It gives the agent a clear map before it starts building tunnels under the house.

The command-line test client is equally important. It gives the agent an executable feedback loop.

And the test cases are the most important part of all.

The Most Valuable Human Work: Writing Tests That Actually Test Something

Here is one thing I learned very quickly:

If you tell an AI agent, “make all tests pass,” it will do that.

Sometimes elegantly.

Sometimes agressively, stopping at nothing, committing every software engineering crime thinkable, just to make the tests pass: Create tests that do not test much. Modify the implementation so it handles the exact test case, but not the real-world behavior behind it. Use try/catch blocks to ignore errors.

This leads to a very specific kind of code smell: the code gets longer, more specific, and more theatrical. Suddenly, your implementation contains special handling for every edge case the test suite happened to mention.

That is why test definition is where I still spend the most careful manual effort.

The key questions are:

  • Does this test represent a real use case?
  • Would it catch an actual regression?
  • Is it too narrow?
  • Is it accidentally encouraging hard-coded behavior?
  • Does the implementation have room to generalize?

The tests do not need to be complete from the beginning. They can evolve. But the first important test cases need to have a spine.

TDD Was Already Useful. Now It Is Agent Fuel.

Writing tests before implementation is obviously not new. That is test-driven development.

But AI agents give TDD a new kind of relevance.

In classic TDD, tests help the developer clarify the goal and avoid regressions.

With AI agents, tests do something more: they create a loop the agent can operate independently.

The agent can run the tests, inspect the failure, change the implementation, run the tests again, and keep going.

That means the test suite becomes more than a safety net. It becomes the steering wheel.

Without tests, the agent is just producing plausible code.

With good tests, the agent has a measurable target.

With bad tests, the agent still has a target — unfortunately it may be the wrong one, and it will sprint toward it with alarming enthusiasm.

Structured Output Files: Less Context, Less Money, Less Pain

Another useful pattern is to persist test script output in structured files on disk.

Instead of forcing the agent to keep huge logs, benchmark results, debug dumps, or intermediate test outputs in the conversation context, the script can write structured files such as JSON, Markdown, or plain text reports.

For example:

test-results/
  latest-summary.json
  failed-cases.json
  performance-report.json
  debug-log.md

This gives the agent a much more efficient way to work.

It can directly inspect the relevant file when needed instead of dragging a giant wall of output through the conversation like a developer moving apartments with no boxes.

This has several advantages:

  • The agent can jump directly to relevant parts.
  • The used context stays smaller.
  • The conversation remains cleaner.
  • Debugging becomes more reproducible.
  • Token usage goes down.
  • And yes: it saves money.

This becomes especially useful for larger test suites, performance benchmarks, computer vision datasets, or anything where the raw output can become huge.

Context is expensive. Noise is expensive. Making the agent read 5,000 lines of logs to find three useful lines is not intelligence — it is invoice generation.

Structured files give the agent a filesystem-based memory that is cheap, targeted, and practical.

A Real Example: Computer Vision Performance

We recently used this workflow in a computer vision framework we built.

We had a larger test dataset and a set of algorithms that could be benchmarked against it. Instead of giving the agent a vague instruction like “make this faster,” we gave it a measurable loop:

  • Run the tests.
  • Try a change.
  • Run the benchmarks.
  • Compare the results.
  • Keep the behavior correct.
  • Improve performance where possible.

With this setup, the agent was able to significantly improve the performance of our algorithms. In one case, runtime went down by about 50%.

That is not magic. That is structure.

The agent was not just “being smart.” It had a safe playground, reliable tests, and measurable feedback. That combination is where AI coding becomes really interesting.

The Developer’s Role Is Changing

AI agents do not remove the need for developers.

They move the developer’s attention.

Less time is spent manually writing every line of implementation code.

More time is spent on:

  • describing the problem clearly,
  • creating executable feedback loops,
  • defining good tests,
  • reviewing architecture,
  • preventing overfitting,
  • keeping the code maintainable,
  • and stopping the agent from becoming a very productive chaos machine.

The better the environment, the better the agent.

If the goal is vague, the tests are weak, and the feedback loop is missing, the agent will still produce something. It may even look impressive. But impressive-looking code is not the same as correct, maintainable software.

That distinction remains very much a human responsibility.

Conclusion

The biggest lesson from the last months is this:

AI agents become dramatically more useful when we stop treating them like autocomplete and start designing our workflow around their strengths.

They are good at iteration.
They are good at running commands.
They are good at reading failures and trying again.
They are good at working inside a clear feedback loop.

They are still weak at reliably testing graphical interfaces.
They can overfit to bad tests.
They can make questionable choices with excellent confidence.

So the solution is not to let them roam freely through the codebase like a caffeinated raccoon.

The solution is to build rails.

Markdown plans.
Command-line entry points.
Good tests.
Structured output files.
Repeatable scripts.
Human review.

Test-driven development was already useful before AI.

But in the age of coding agents, TDD becomes something even more powerful: a way to let AI work independently without losing control over the result.

Or, put differently:

The future of AI-assisted development may not belong to the person who writes the best prompts.

It may belong to the person who builds the best feedback loops.