add test for override parent

rules-tests/DowngradePhp82/Rector/FunctionLike/DowngradeStandaloneNullTrueFalseReturnTypeRector/Fixture/override_parent_method.php.inc

@@ -0,0 +1,34 @@
+<?php
+
+namespace Rector\Tests\DowngradePhp82\Rector\Class_\DowngradeStandaloneNullTrueFalseReturnTypeRector\Fixture;
+
+use Rector\Tests\DowngradePhp82\Rector\FunctionLike\DowngradeStandaloneNullTrueFalseReturnTypeRector\ParentClass;
+
+final class OverrideParentMethod extends ParentClass
+{
+    public function run(): null
+    {
+        return null;
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\DowngradePhp82\Rector\Class_\DowngradeStandaloneNullTrueFalseReturnTypeRector\Fixture;
+
+use Rector\Tests\DowngradePhp82\Rector\FunctionLike\DowngradeStandaloneNullTrueFalseReturnTypeRector\ParentClass;
+
+final class OverrideParentMethod extends ParentClass
+{
+    /**
+     * @return null
+     */
+    public function run(): ?string
+    {
+        return null;
+    }
+}
+
+?>

rules-tests/DowngradePhp82/Rector/FunctionLike/DowngradeStandaloneNullTrueFalseReturnTypeRector/Source/ParentClass.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Tests\DowngradePhp82\Rector\FunctionLike\DowngradeStandaloneNullTrueFalseReturnTypeRector;
+
+class ParentClass
+{
+    public function getSomeString(): ?string
+    {
+        return 'test';
+    }
+}