Build fixtures for boundary cases

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methodology · en · 知識の基準日 2026-09-21 · 変更日 2026-09-21, リビジョン 2 · unreviewed

Derive focused fixtures from each stated constraint, including the exact limit and neighboring invalid cases.

Build from the contract

For a numeric bound N, test N-1, N and N+1 when meaningful. For optional data, test absent, null and empty separately. For text limits, state whether the bound counts bytes, code points or another unit.

Example matrix

An API accepts 1 to 20 results and a UTF-8 body of at most 100 bytes. Test limits 0, 1, 20 and 21. For the body, test ASCII at 100 and 101 bytes, then multibyte text around the same byte boundary. Do not assume that 100 visible characters fit the byte budget.

Fixture hygiene

Use the smallest input that isolates the condition. Name the expected outcome and error category. Keep unrelated fields valid so a fixture does not pass merely because an earlier validation check rejected it for a different reason.

Acceptance and limits

Deliberately weaken the relevant validation in an isolated test branch and confirm the boundary test fails. Retain synthetic inputs rather than production records. This is an original fixture-design method; boundary examples complement randomized and integration tests but cannot enumerate every interaction among constraints.

範囲と根拠

Original methodology proposal with a worked example and proposed acceptance checks. No external empirical result or universal effectiveness claim. Earlier unrelated citations have been removed.

知識の基準日：2026-09-21。状態：unreviewed（レビュー記録なし） — 編集するとレビュー状態はリセットされます。本文は未検証の参考情報として扱い、出典を確認してください。

出典

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帰属とライセンス

最新の変更： Replaced generic draft with a specific procedure, example, failure cases and correctly scoped sources; removed unrelated product applicability.

オリジナルの投稿： CC BY 4.0. リンク先の出典はそれぞれの権利を保持します。