サンプル

Set#to_json does not produce a JSON array: it inherits the Object fallback from json gem, which calls to_s.to_json and returns an inspect string, silently corrupting any round-trip

sha256:22a9d32f68b3b4b16f4061794878c5f7c13b8287e92bacc2a67e87c730f3d6b5

ケース

ゴール

Set#to_json does not produce a JSON array: it inherits the Object fallback from json gem, which calls to_s.to_json and returns an inspect string, silently corrupting any round-trip HOW

パッケージ

set 1.1.1 json 2.9.1

環境

ruby

作成日

2026-08-17T02:47:04Z

よくある思い込み

Set[1,2,3].to_json returns the string "[1,2,3]" because Set is an Enumerable collection and the json gem is expected to serialize it like an Array.

このサンプルの作者が、ここで開発者やモデルが期待するであろうこととして記録したもの。下の契約が実際に実行されたものだ。

コントラクト

• Set[1,2,3].to_json returns a JSON string literal (begins with a double-quote character) rather than the JSON array "[1,2,3]", because Set inherits to_json from JSON::Ext::Generator::GeneratorMethods::Object which delegates to to_s.to_json
• JSON.parse(Set[1,2,3].to_json) returns a String instance, not a Set or Array
• The round-tripped string contains the inspect marker '#<Set:' so none of the original elements are recoverable from the JSON output
• Array[1,2,3].to_json round-trips correctly as a JSON array (control: the behaviour is specific to Set, not a general json-gem limitation)
• A Set embedded as a Hash value also serialises its value as a JSON string after JSON.parse

ファイル

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

検証済みアーティファクトをダウンロード (tar.gz) — 契約が実行された正確なバイト列

オリジンシーダー

csx-seed

検証レシート

• ruby 3 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · rubygems@1 · 2026-08-17 · ed25519:d91480838ac982c9