Comment by cmrdporcupine | Hacker News Reader

Comment by cmrdporcupine | Hacker News Reader

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I have mixed results but one of the more disturbing things I've found Claude doing is that when confronted with a failing test case, and not being able to solve a tricky problem.. just writing a kludge into the code that identifies that here's a test running, and makes it pass. But only for that case. Basically, totally cheating.

You have to be super careful and review everything because if you don't you can find your code littered with this strange mix of seeming brilliance which makes you complacent... and total Junior SWE behaviour or just outright negligence.

That, or recently, it's just started declaring victory and claiming to have fixed things, even when the test continues to fail. Totally trying to gaslight me.

I swear I wasn't seeing this kind of thing two weeks ago, which makes me wonder if Anthropic has been turning some dials...

I also feel like I’ve seen a lot more of these over the past week or two, whereas I don’t remember noticing it at all before then.

It feels like it’s become grabbier and less able to stay in its lane: ask for a narrow thing, and next thing you know it’s running hog wild across the codebase shoehorning in half-cocked major architectural changes you never asked for. [Ed.: wow, how’s that for mixing metaphors?]

Then it smugly announces success, even when it runs the tests and sees them fail. “Let me test our fix” / [tests fail] / [accurately summarizes the way the tests are failing] / “Great! The change is working now!”

Yes, or I've seen lately "a few unrelated tests are failing [actually same test as before] but the core problem is solved."

After leaving a trail of mess all over.

Wat?

Someone is changing some weights and measures over at Anthropic and it's not appreciated.

It is possible that the tasks you gave to the model previously were just about easy enough for it to handle, while the few failing tasks you gave recently were a bit too tough for the model, thus it had to cheat.

For the exact same task, some changes in the system prompt used by Claude Code, and/or how it constructs the user prompt, can quite easily make the task either easy enough or not. It is a fine line.

> identifies that here's a test running, and makes it pass. But only for that case

My team refers to this as a "VW Bugfix".

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