[CodeQuality] Skip NarrowUnusedSetUpDefinedPropertyRector for property used in nested closure

rules-tests/CodeQuality/Rector/Class_/NarrowUnusedSetUpDefinedPropertyRector/Fixture/skip_property_used_in_closure.php.inc

@@ -0,0 +1,25 @@
+<?php
+
+namespace Rector\PHPUnit\Tests\CodeQuality\Rector\Class_\NarrowUnusedSetUpDefinedPropertyRector\Fixture;
+
+use PHPUnit\Framework\TestCase;
+
+final class SkipPropertyUsedInClosure extends TestCase
+{
+    private array $dataSource;
+
+    protected function setUp(): void
+    {
+        $this->dataSource = [1, 2, 3];
+
+        $this->resolver = function () {
+            return $this->dataSource;
+        };
+    }
+
+    public function test()
+    {
+        $resolver = $this->resolver;
+        $this->assertSame([1, 2, 3], $resolver());
+    }
+}

rules/CodeQuality/Rector/Class_/NarrowUnusedSetUpDefinedPropertyRector.php

@@ -6,6 +6,7 @@
 
 use PhpParser\Node;
 use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\Closure;
 use PhpParser\Node\Expr\PropertyFetch;
 use PhpParser\Node\Expr\Variable;
 use PhpParser\Node\Stmt\Class_;
@@ -121,6 +122,12 @@ public function refactor(Node $node): ?Node
                 continue;
             }
 
+            // referenced inside a nested closure that may run after setUp() - turning it into a local
+            // variable would leave it out of the closure scope, as there is no "use" binding to add it
+            if ($this->isPropertyUsedInNestedClosure($setUpClassMethod, $propertyName)) {
+                continue;
+            }
+
             $hasChanged = true;
 
             unset($node->stmts[$key]);
@@ -189,6 +196,35 @@ private function isPropertyUsedOutsideSetUpClassMethod(
         return $isPropertyUsed;
     }
 
+    private function isPropertyUsedInNestedClosure(ClassMethod $setUpClassMethod, string $propertyName): bool
+    {
+        // only regular closures are unsafe: they do not capture outer variables without an
+        // explicit "use" binding. Arrow functions auto-capture by value, so narrowing is safe there.
+        $closures = $this->nodeFinder->findInstanceOf($setUpClassMethod, Closure::class);
+
+        foreach ($closures as $closure) {
+            $usedPropertyFetch = $this->nodeFinder->findFirst($closure, function (Node $node) use (
+                $propertyName
+            ): bool {
+                if (! $node instanceof PropertyFetch) {
+                    return false;
+                }
+
+                if (! $this->isName($node->var, 'this')) {
+                    return false;
+                }
+
+                return $this->isName($node->name, $propertyName);
+            });
+
+            if ($usedPropertyFetch instanceof PropertyFetch) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     private function shouldSkipProperty(
         bool $isFinalClass,
         Property $property,