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Comment by johnfn | Hacker News Reader

What code is fully, or even primarily, tested by a human? Haven't you heard of automated testing suites, regression testing, conformance testing..?

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If I were to mirror your tone, I'd ask you if you've ever heard of the basic courtesy of running your code manually yourself before you waste anyone else's time with it... Or whether you've heard about QA, or about making demos for Product or for customers...

Neither of these can be replaced by an automated test suite of any kind, and all of these are examples of good engineering practices that guarantee software quality.

Additionally, even if you don't (need to) adhere to the best engineering practices and instead rely solely on an automated test suite, the tests in this suite must be validated - read and understood - by a human in order to guarantee that they nail down the correct requirements.

Test code written by a human counts as "tested by a human". Also, most code is literally tested (manually) by humans in addition to automated tests. You are being pointlessly pedantic.

Bun has a test suite of tens of thousands of tests. For purely non-functional changes, like refactors or rewrites (e.g. a Rust rewrite) I rely primarily on test suites, not manual testing, in order to ensure that nothing regressed. I mean, sure, I am going to poke around, too, but the test suite is the encoding of thousands of obscure bugs and issues over years. There is no way my manual testing will be able to cover the same ground.

> Test code written by a human counts as "tested by a human".

Were Bun's tests generated by an LLM? If they were, were they read by a human afterwards to be validated?

Publicly based on my calculations[1] there only ~20k tests. I would say they are usual tests for the runtime. Constantly running on the CI much lesser amount. Average test count/line of code ratio drops after rewrite. And even before Node have denser tests count/LOC ratio

[1] https://kant2002.github.io/en/llm/2026/05/16/bun-pr-analysis...

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