Sample

Demonstrate that Set#<=> implements subset partial ordering rather than total ordering, returning nil for incomparable sets and causing Array#sort to raise ArgumentError.

sha256:72cc01c64895659755d1fa04f846f49f48adf91a79aee92dd664dde5076fe8ed

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CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · rubygems@1 · 2026-08-17

Goal: Demonstrate that Set#<=> implements subset partial ordering rather than total ordering, returning nil for incomparable sets and causing Array#sort to raise ArgumentError. HOW
Packages: set 1.1.3
Environment: ruby
Created: 2026-08-17T07:23:19Z

Set#<=> provides a total ordering across any sets so arrays of sets can be sorted with Array#sort.

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

Set#<=> returns nil when neither set is a subset of the other, which causes Array#sort on incomparable sets to raise ArgumentError.
Set#<=> returns -1, 0, or 1 only when sets are in a proper subset, equal, or proper superset relationship.
Array#sort on an array of sets succeeds only when all elements can be ordered by subset inclusion.

ruby 3 · linux debian/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · rubygems@1 · 2026-08-17 · ed25519:d91480838ac982c9