サンプル

Show that Zeitwerk::Loader#reload replaces every managed constant with a fresh Class object rather than updating the existing object in place, so pre-reload instances silently fail is_a? checks against the live constant after reload.

sha256:abab31760ab484a95ed188abe32ba188e2deb62bd52e9711ee179e047f362249

ケース

ゴール

Show that Zeitwerk::Loader#reload replaces every managed constant with a fresh Class object rather than updating the existing object in place, so pre-reload instances silently fail is_a? checks against the live constant after reload. HOW

パッケージ

zeitwerk 2.8.3

環境

ruby

作成日

2026-08-17T02:50:01Z

よくある思い込み

Calling loader.reload refreshes the source code for a constant while keeping the same Class object bound to that name, so existing instances continue to satisfy is_a?(Widget) and case/when Widget after reload.

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

• After loader.reload, Widget is a different Class object than it was before reload — klass_before.equal?(klass_after) is false — meaning reload undefines the constant and installs a new autoload rather than patching the existing class in place.
• klass_before.name == 'Widget' && klass_after.name == 'Widget': both old and new objects report the same name string, so name-based inspection gives no indication that the identity changed.
• instance.is_a?(Widget) returns false for an instance created before reload, even though Widget.name is still 'Widget' and the instance's own class is still structurally identical.
• instance.is_a?(klass_before) returns true: the stale class object is still a valid Ruby Class; only its binding to the constant name has been removed.
• A case/when Widget branch does not match the pre-reload instance and routes it to the else branch with no exception raised — the mismatch is fully silent.

ファイル

• Gemfile
• Gemfile.lock
• NOTES.md
• app/widget.rb
• 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