Mutation testing counts uncovered code

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+- Mutation testing now counts code the tests execute without naming it in `#[Covers]`
+  (`infection --with-uncovered`), with `PublicVisibility` off and default-parameter
+  signature lines ignored; unit test added for the docblock splitter failing (`preg_split` returning false). No `src/` changes.
+
 ## 1.0.1 — 2026-09-27
 
 - Package `type` changed to `rector-extension` so the rule pack is discoverable on Packagist (`type=rector-extension`) and recognised by `rector/extension-installer`. No rules are auto-applied: no `extra.rector.includes` key is declared, so `rector.php` still opts in explicitly.

composer.json

@@ -77,7 +77,10 @@
         ],
         "cs": "php-cs-fixer fix --dry-run --diff --config=.php-cs-fixer.php",
         "cs:fix": "php-cs-fixer fix --diff --config=.php-cs-fixer.php",
-        "mutation": "infection --threads=max",
+        "mutation": [
+            "Composer\\Config::disableProcessTimeout",
+            "infection --threads=max --with-uncovered"
+        ],
         "psalm": "psalm --no-cache",
         "rector": "rector process --dry-run",
         "rector:fix": "rector process",

infection.json5

@@ -22,6 +22,24 @@
     "testFramework": "testo",
     "minMsi": 100,
     "mutators": {
-        "@default": true
+        "@default": true,
+        // Constructor/method parameter declarations with a default value
+        // (`private int $x = 100,`, `bool $strict = false,`): the mutant sits on a
+        // signature line with no executable opcode under pcov, so it is reported Not
+        // Covered whatever the tests do. Only a type-prefixed `$name = default,` line
+        // matches; a body line cannot (no type before the variable). Do NOT add ^ or $:
+        // Infection wraps the pattern as ^-\s*REGEX$ over the removed diff line.
+        // Verified 2026-11-01 by diffing the survivor lists with and without it:
+        // bulkhead 6, circuit-breaker 13, json-ld 19 mutants removed, all of them
+        // such signature lines; Escaped and Timed Out unchanged.
+        "global-ignoreSourceCodeByRegex": [
+            "(?:(?:private|protected|public|readonly)\\s+)*\\??[A-Za-z_\\\\][\\w\\\\|]*\\s+\\$\\w+\\s*=\\s*[^,;]+,"
+        ],
+        // Off: with --with-uncovered a PublicVisibility mutant sits on a parameterless
+        // method's signature line, which has no executable opcode under pcov/xdebug,
+        // so it is reported Not Covered and can never be killed, whatever #[Covers]
+        // says. Measured on pinned-http-client 2026-11-01: 4 of 4 such mutants were
+        // Not Covered, none killed.
+        "PublicVisibility": false
     }
 }

tests/DocblockTypeRewriterTest.php

@@ -32,6 +32,32 @@ public function rewritesReturnTags(string $docText, ?string $expected): void
         Assert::same((new DocblockTypeRewriter())->rewrittenReturnTag($docText), $expected);
     }
 
+    public function aDocblockThePatternEngineCannotSplitIsLeftAlone(): void
+    {
+        // PCRE keeps compiled patterns (JIT included) in a bounded cache and a
+        // JIT-compiled match ignores the backtrack limit: evict, then recompile
+        // without JIT so that the limit applies to the split.
+        for ($i = 0; $i < 5_000; ++$i) {
+            preg_match('/evict' . $i . '/', '');
+        }
+
+        $jit = ini_set('pcre.jit', '0');
+        $limit = ini_set('pcre.backtrack_limit', '1');
+        set_error_handler(static function (int $severity, string $message): never {
+            throw new \ErrorException($message, 0, $severity);
+        });
+
+        try {
+            $rewritten = (new DocblockTypeRewriter())->rewrittenVarTag("/**\n * @var DateTime\n */");
+        } finally {
+            restore_error_handler();
+            ini_set('pcre.backtrack_limit', (string) $limit);
+            ini_set('pcre.jit', (string) $jit);
+        }
+
+        Assert::null($rewritten);
+    }
+
     public static function varTagProvider(): iterable
     {
         yield 'plain type' => [