Sample

Set#divide with a 2-arity block applies transitive closure (union-find) across all element pairs, not pairwise grouping, so elements connected through intermediaries collapse into one partition

sha256:081685a24f8921c237110315b32c09809d9d3c38413eb03da335108348d877e8

Case

Goal

Set#divide with a 2-arity block applies transitive closure (union-find) across all element pairs, not pairwise grouping, so elements connected through intermediaries collapse into one partition HOW

Packages

set 1.1.1

Environment

ruby

Created

2026-08-16T16:53:43Z

Commonly assumed

Set#divide with a 2-arity predicate block partitions elements by directly evaluating the block on every pair and grouping each matching pair together, so Set[1,2,3,4].divide { |a,b| (a-b).abs == 1 } produces multiple partitions matching the adjacent pairs rather than collapsing all transitively-connected elements into one.

The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.

Contract

• Set[1,2,3,4].divide { |a,b| (a-b).abs == 1 } returns a single partition containing all four elements rather than multiple pairwise groups, because the 2-arity form performs a transitive-closure (union-find) over all pairs, merging 1-2, 2-3, and 3-4 into one equivalence class
• assert result.size == 1 and result.first == Set[1,2,3,4]
• assert adding an isolated element (100) produces exactly two partitions: {1,2,3,4} and {100}
• assert Set#divide returns a Set of Sets while Set#classify returns a Hash keyed by block return value — they are not interchangeable
• assert Set#divide with a 1-arity block groups by block return value without transitivity, yielding as many partitions as there are distinct block values
• assert Set#divide on an empty Set returns an empty Set, not nil

Files

• Gemfile
• Gemfile.lock
• NOTES.md
• csx.json
• test/contract.rb

Download the verified artifact (tar.gz) — the exact bytes the contract ran against

Origin Seeder

csx-seed

Verification receipts

• ruby 3 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · rubygems@1 · 2026-08-16 · ed25519:d91480838ac982c9