fix: use range-aware shrinker in Int64Range to stay within bounds#92
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untoldwind merged 1 commit intoApr 20, 2026
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Int64Range used the generic Int64Shrinker which shrinks toward 0, producing values outside the [min, max] range during shrinking. While the Sieve filters these out, some property-based test frameworks (like stateful commands) may not apply the sieve during the shrink phase, causing panics from out-of-bounds values. Add int64RangeShrinker that shrinks toward min by halving the distance from min, guaranteeing all shrunk values stay within [min, max]. Fixes leanovate#81
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It might be a good idea to also "shrink" to the max value of the interval as the boundary condition might happen there. |
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Fixes #81
Problem
gen.IntRange(min, max)uses the genericInt64Shrinkerwhich shrinks toward 0. When the range doesn't include 0 (e.g.,IntRange(5, 10)), the shrinker produces values outside the range during shrinking.While the
Sievefilters these out in some contexts, stateful command-based tests may not apply the sieve during the shrink phase, causing panics from out-of-bounds values.Fix
Add a range-aware
int64RangeShrinker(min, max)that shrinks towardminby halving the distance frommin, guaranteeing all shrunk values stay within[min, max].All existing tests pass with
-race.