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Comment by cronin101 | Hacker News Reader

    Forall A:
    add(A, 0) == A

    Forall A B C:
    add(add(A,B), C) == add(A, add(B, C))

I think that’s sufficient. Rule 101 of useful testing is understanding the actual constraints you rely on.

Maybe throw in add(A, B) == add(B, A) if you’re angling for a promotion…

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    add(a, b) => a == 1 && b == 1 ? 1 : a + b

Kinda disappointing your test would take so long to run and still catch a simple error.

> your test would take so long to run

I think GP's test would probably be implemented with property testing (or even better, symbolic execution). It wouldn't necessarily take super long to run.

How difficult would it be to write a proper test with one of those systems for something more complex when even this trivial example doesn't have solution yet?

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