i love gambling. i have used “AI” extensively. it feels the same.
So, look. One shot rewriting the whole test suite in another language is probably not great to do, but what happened here is so much worse than you are expecting.
▻https://github.com/RsyncProject/rsync/pull/903
This does not “translate tests into pytest” or a unit testing framework, it writes its own testing framework where tests are whole python scripts that redefine basic test functions in every script. Surely there would be a single way to “run rsync and get the results” - nope, well, there is, but then every test file will randomly redefine its own _run_and_capture function. So like now rsync needs a test suite for its test suite.
If instead of telling an LLM to “rewrite the tests in python” you just searched “python testing” you would find the pytest docs. And then you would find examples. And then you could write fixtures to deduplicate all the prior shell script setup and teardown stuff, and so on. But since it was just “rewrite the tests in python” its now worse than before, and the odds of the rewrite actually being a 100% faithful translation are close to 0.
I think the modal situation here is that the people are reading none or very little of what is being generated by the LLM, so the tests have a special role: Tests function as the pull arm on the slot machine, you just generate until tests pass, and that’s a jackpot. Obviously that’s meaningless when the tests are meaningless, so tests take on a very different meaning and role in slot machine coding.
Previously we would write careful test conditions that were based off some real problem or an understanding of what the code under test did, and had a specific thing they were intended to protect against. Tests move slow and are designed to protect us against the things we know can go wrong. When we learn of a new wrong thing, we add a test.
LLM tests have the form of tests but don’t do the same thing. They often test nothing, and are just expressions of truisms that the probabilistic text space explored while generating. They have strongly worded names but end up actually asserting that basic language features work as expected. Because it is not us writing tests for ourselves, where we only harm ourselves by making them weak, they function instead as a passively obfuscated justification for the code that the LLM generates. The user wants the tests to pass. The LLM provides.
The tests are theater: they are the play field for the slot machine. They are mild, surmountable, need to fail a few times to be plausible, but must eventually pass within the expected generation loop window to deliver the payout.
Here’s an example from some code that was thrust at me this week. The rest of the tests try a bit harder to look like tests, but this one is perplexing.
What does it test? The function name suggests its a smoke test. LLMs love to call things smoke tests. That would suggest this would be an early-run test that fails loudly if some basic precondition - like having ffmpeg - fails. Or, I guess we are smoke testing the ensure_ffmpeg function? Anyway who knows. However we first check if ffmpeg or ffprobe are present, which is exactly what ensure_ffmpeg does. If they aren’t present, a warning tells us that ffmpeg/ffprobe are required for the video tests, which makes it seem like this should be a parameterizing test that controls which tests are run, which of course it does not do.
So the test literally does nothing and cannot possibly fail, but says it does at least two things, because to an LLM something saying it does something is the same thing as it actually doing that thing.
Edit: I’m seeing some comments that suggest ppl think this example is from rsync, as said at top, this is just an example that came my way in a different project and I’m using it to illustrate a common LLM test problem.
