Try Rector Online | Rector - Automated Way to Instantly Upgrade and Refactor any PHP code

Run Rector on your code to see what it can do for you:

 <?php
 
+declare(strict_types=1);
+
 use PHPUnit\Framework\TestCase;
 
 final class DemoTest extends TestCase

     {
         $var = testFunction(true);
         
-        $this->assertNotNull($var);
+        $this->assertInstanceOf(\stdClass::class, $var);
     }
     
     public function testIsNull()

     {
 		$var = testFunction(false);
         
-        $this->assertNull($var);
+        $this->assertNotInstanceOf(\stdClass::class, $var);
     }        
 }

     }
     
     return null;
}

PHP snippet to change

<?php

use PHPUnit\Framework\TestCase;

final class DemoTest extends TestCase
{
	public function testIsNotNull()
    {
        $var = testFunction(true);
        
        $this->assertNotNull($var);
    }
    
    public function testIsNull()
    {
		$var = testFunction(false);
        
        $this->assertNull($var);
    }        
}

function testFunction(bool $switch): ?stdClass
{
    if ($switch === true) {
        return new stdClass();
    }
    
    return null;
}

Applied Rules:

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Config rector.php

<?php

use Rector\Config\RectorConfig;

return RectorConfig::configure()
    ->withPhpSets(php83: true)
    ->withComposerBased(phpunit: true)
    ->withPreparedSets(phpunitCodeQuality: true);

Rector version: fa3b72 - released at 2026-08-29 22:08