@RayFernando1337: I find the latest models write a lot of unit tests. Most of them restate the code they were written after, so they alwa…
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A tweet criticizes AI models for writing ineffective unit tests and shares a prompt to enforce better testing practices, emphasizing E2E tests and avoiding unit tests written after code.
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I find the latest models write a lot of unit tests. Most of them restate the code they were written after, so they always pass and catch almost nothing. They run fast, but they break on every refactor and the agent burns time fixing tests instead of the feature.
The prompt I used to clean out mine, adopted from Ansh is:
“This repo is full of low-signal unit tests. Delete every one that wouldn’t catch a real bug our E2E tests miss. Fan the work out across parallel subagents.
Then add these rules to AGENTS.md so future agents stop writing them.
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Never write unit tests after you write code.
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Highly prefer E2E tests as the sole testing mechanism. Use them to verify complex features work. At the end of E2E tests, produce a verifiable and repeatable artifact.
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If you must test a system in isolation, first write down all the ways it could fail, then write the code.“
Ansh Nanda (@anshnanda): At the top of my AGENTS.md:
- NEVER write unit tests after you write code.
- Highly prefer E2E tests as the sole testing mechanism. Use them to verify complex features work. At the end of E2E tests, produce a verifiable and repeatable artifact.
- If you must test a system in
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