AddInstanceofAssertForNullableArgumentRector

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Add explicit instance assert between above nullable object pass

 use PHPUnit\Framework\TestCase;

 final class SomeTest extends TestCase
 {
     public function test()
     {
         $someObject = $this->getSomeObject();
+        $this->assertInstanceOf(SomeClass::class, $someObject);

         $this->process($someObject);
     }

     private function getSomeObject(): ?SomeClass
     {
         if (mt_rand(0, 1)) {
             return new SomeClass();
         }

         return null;
     }

     private function process(SomeClass $someObject): void
     {
         // non-nullable use here
     }
 }

Configure your rector.php:

<?php

use Rector\Config\RectorConfig;
use Rector\PHPUnit\CodeQuality\Rector\ClassMethod\AddInstanceofAssertForNullableArgumentRector;

return RectorConfig::configure()
    ->withRules([
        AddInstanceofAssertForNullableArgumentRector::class,
    ]);