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by boulos20 hours ago |
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upvoteby Groxx18 hours ago|
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particularly "and fuzzing", yea. fuzzing generally does intentionally explore boundary values, from what I've seen. for an encoding library like this, I think it's fair to say that fuzzing is a baseline expectation for any decent code, and it almost certainly would've caught this in seconds.

--- edit

concretely, I made a very simple round-trip test with proptest, and got dozens of failures and this in less than a second:

    thread 'signed_round_trip' (50528) panicked at tests/test.rs:72:1:
    Test failed: attempt to multiply with overflow.
    minimal failing input: value = 4611686018427387904
        successes: 2
        local rejects: 0
        global rejects: 0
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upvoteby fjdjshsh19 hours ago|
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Maybe it's not something they would "typically miss", but, from proof by existence, it's something they sometimes miss.

It does speak to the benefits of using lean in that you don't need to be clever about the different examples you test.

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upvoteby Exoristos19 hours ago|
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Yes, it's basic QA. If tests missed this kind of thing, they would be of much more limited use than we generally expect them to be. It raises questions about the authors' background.
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upvoteby Quekid516 hours ago|
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Because this is garbage PR. That's it.

Every property-based testing system (invented ca. 1980) will explore boundary values. The semantics (or lack thereof) of C and C++ can make this difficult to actually test for because the compiler is allowed to say "test passed" to any input leading to UB.

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upvoteby vlovich12315 hours ago|
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Property based testing is good at generating boundary values for inputs. But for any more complicated piece of code getting boundary value coverage of interior values is an open problem that requires instrumentation feedback to understand branch coverage and value coverage of the code that got tested. It’s not an easy thing at all.
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upvoteby teiferer7 hours ago|
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> The semantics (or lack thereof) of C and C++ can make this difficult to actually test for because the compiler is allowed to say "test passed" to any input leading to UB.

I get what you are saying but does this actually apply to a test? If the code under test is in one compilation unit and the test harness in another and they are linked together then the UB optimization issue ends at the API boundary and can't possibly make the test pass ..?

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upvoteby pierrefermat120 hours ago|
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[flagged]
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upvoteby fjdjshsh19 hours ago|
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I feel this is a lazy, straw-manning comment.
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