Comment by gr_norm
11 hours ago
From the article:
> Proving that a fuzz test has no more crashes to find is more significant than it sounds. It’s common for fuzz tests in real-world code to test for violations of meaningful high-level properties, such as encode-decode roundtripping, idempotence, algebraic laws, differential testing, self-consistency, or equivalence to reference implementations. For example, a fuzz test for the LZO compression algorithm asserts that if you compress an input, then decompress it, the result is the same as the original. If the property does not hold, the program crashes—so proving the test never crashes is equivalent to proving the property itself.
However, you're correct that this is not formal verification in the sense of a correctness proof against a full specification validated to capture what the program is intended to do. Pretty impressive though.
In essence this lets you verify any property you want for a given function, as long as it can be expressed as a fuzz test. Specifically, you can express your property with an assert, and then prove that it never fires. This is nice because it keeps everything in one language, rather than having to translate the whole program into Rocq and then express your desired property as a Rocq theorem.
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