[CodeQuality] Skip by-ref use() closures in CallbackSingleAssertToSimplerRector (#715)

Author: TomasVotruba

rules-tests/CodeQuality/Rector/MethodCall/CallbackSingleAssertToSimplerRector/Fixture/skip_referenced_use.php.inc

@@ -0,0 +1,23 @@
+<?php
+
+namespace Rector\PHPUnit\Tests\CodeQuality\Rector\MethodCall\CallbackSingleAssertToSimplerRector\Fixture;
+
+use PHPUnit\Framework\TestCase;
+
+final class SkipReferencedUse extends TestCase
+{
+    public function test()
+    {
+        $download = null;
+
+        $builder = $this->getMockBuilder('AnyType')->getMock();
+
+        $builder->expects($this->once())
+            ->method('detach')
+            ->with($this->callback(function ($downloadDetach) use (&$download): bool {
+                $this->assertSame($downloadDetach, $download);
+
+                return true;
+            }));
+    }
+}

rules/CodeQuality/Rector/MethodCall/CallbackSingleAssertToSimplerRector.php

@@ -125,6 +125,13 @@ private function matchCallbackSoleAssertSameExpected(Expr $expr): ?Expr
             return null;
         }
 
+        // skip closures capturing by reference, as the referenced value is likely modified above
+        foreach ($innerClosure->uses as $use) {
+            if ($use->byRef) {
+                return null;
+            }
+        }
+
         // exactly assertSame() expression + "return true;"
         $closureStmts = $innerClosure->getStmts();
         if (count($closureStmts) !== 2) {