What syntax is needed to fix this php unit test?

Never php unit tested before - looked at multiple stack overflow posts still cant get it working.

Output window

<?php

namespace UnitTestFiles\Test;
use PHPUnit\Framework\TestCase;

class FirstTest extends TestCase {
    

public function FirstTest() {
  $sscoretest1 = 10;

$sscoretest2 = $sscoretest1 / 20 * 100; 

echo $sscoretest2; 
  
   require('test.php');
   $this->expectOutputString('50');
}

}

?>