test: add assertType coverage for untested type inference cases#80
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- isErr() narrowing (annotation existed but was untested) - instanceof narrowing on the true branch (pins known limitation: generics are lost, unwrap() becomes mixed) - match expression arm narrowing via instanceof (mixed) vs isOk() (preserves Ok<int>/Err<RuntimeException>) - match() method return type composition (U|V) - inspect()/inspectErr() type preservation - callback parameter inference for isOkAnd/isErrAnd/inspect/inspectErr - constructor inference for new Ok / new Err - conditional return resolution of unwrap/unwrapErr on generic receiver - unwrapOr/unwrapOrElse on concrete Ok/Err receivers
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #80 +/- ##
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Coverage 100.00% 100.00%
Complexity 40 40
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Files 2 2
Lines 80 80
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Hits 80 80
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Code Review
This pull request adds several PHPStan type assertion tests for the Result type (Ok/Err), covering type narrowing with isErr() and instanceof, match expressions, callback parameter inference, and unwrap variants. The review feedback correctly identifies that using never as a parameter type hint in a closure (line 267) is invalid in PHP and will cause a fatal error, suggesting to remove the type hint and let PHPStan infer it.
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| { | ||
| assertType('int', $ok->unwrap()); | ||
| assertType('int', $ok->unwrapOr($default)); | ||
| assertType('int', $ok->unwrapOrElse(static fn (never $e): float => $fallback)); |
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PHPでは never 型は戻り値専用の型（return-only type）であり、関数の引数の型ヒントとして使用することはできません。このコードを実行しようとすると、Fatal error: Type never can only be used as a return type が発生します。
PHPStanの静的解析用ファイルであり直接実行されない場合でも、無効なPHP構文を避けるために、引数の型ヒントから never を削除することをお勧めします。unwrapOrElse の定義から、PHPStanは引数 $e を自動的に never として推論します。
assertType('int', $ok->unwrapOrElse(static fn ($e): float => $fallback));There was a problem hiding this comment.
Pull request overview
This PR expands PHPStan assertType coverage in tests/Types/result.php to validate previously untested type-inference and narrowing behaviors (notably isErr()-based narrowing, match expression arm narrowing, and callback/constructor inference), without changing the library implementation in src/.
Changes:
- Add
isErr()narrowing tests to cover both true/false branches (Err<E>vsOk<T>). - Add new coverage for
matchexpression arm narrowing andResult::match()return-type composition. - Add coverage for callback parameter inference, constructor inference (
new Ok(...)/new Err(...)), and conditional return types onunwrap*variants.
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Summary
tests/Types/result.phpの assertType 型テストを拡充し、アノテーションは実装済みなのに検証されていなかったケース（isErr()ナローイング等）と、match式・コールバック推論まわりの未カバーケースを追加する。ライブラリ本体（src/）の変更はなし。Changes
isErr()ナローイング:@phpstan-assert-if-true Err<E>/@phpstan-assert-if-false Ok<T>の両分岐を検証（これまでisOk()側のみテストされていた）instanceofナローイングの true 側分岐: 既知の制限としてピン留め — ジェネリクスが失われOk（型引数なし）になりunwrap()はmixedになるmatch式のアーム内ナローイング:instanceofアームではmixedになる一方、isOk()アームならunwrap()がintに解決されることを対で検証match()メソッド: 戻り値が両コールバックの戻り値型U|V（float|string）に合成されることを検証inspect()/inspectErr():Result<int, RuntimeException>を変えないことを検証isOkAnd/isErrAnd/inspect/inspectErrに渡した型宣言なしクロージャの引数がint/RuntimeExceptionに推論されることを検証new Ok($int)→Ok<int>、new Err($e)→Err<RuntimeException>Resultレシーバでのunwrap()/unwrapErr()、および具象Ok/ErrレシーバでのunwrapOr()/unwrapOrElse()が実行時に起こり得ない側の型を混ぜないことを検証Notes
instanceofベースの絞り込みはジェネリクスを失う（isOk()/isErr()経由なら保たれる）ことが判明。既存のtestInstanceofNarrowingが型引数なしのErrを期待していたのはこれが理由。該当テストには「既知の制限」コメントを付け、isOk()版の推奨を明記したnew Ok(42)→Ok<42>、fn => 0.5→0.5）を避けるため、リテラルではなく引数経由で値を渡しているVerification
phpstan analyse（level max）✅ /php-cs-fixer fix --dry-run✅ /phpunit --no-coverage✅ (69 tests, 111 assertions)