Disable trigger_error() for only one test in PHPUnit

BarTest.php

<?php

namespace MyNamespace;

use PHPUnit\Framework\TestCase;
use PHPUnit_Framework_Error_Warning as WarningError;

class BarTest extends TestCase
{
    private $object;

    private $errorHandler;

    private $expectedErrors = 0;

    protected function setUp()
    {
        $this->object = new Bar;
        $this->errorHandler = set_error_handler([$this, 'handleErrors']);
    }

    protected function tearDown()
    {
        restore_error_handler();
        $this->expectedErrors = 0;
    }
    
    // this is the test which expectes a trigger_error(…, E_USER_WARNING)
    public function testFooTriggerEUserWarning()
    {
        $this->expectException(WarningError::class);
        $this->object->foo();
    }
    
    //this is the test which should ignore the trigger_error() and check the return value
    public function testFooReturnsValue()
    {
        set_error_handler(function () {});
        $this->expectedErrors = E_USER_WARNING;
        // $this->assertSame(…, $this->object->foo());
    }
    
    public function handleErrors($errno, ...$args)
    {
        // expected error type
        if ($this->expectedErrors & $errno) {
            return;
        }

        call_user_func($this->errorHandler, $errno, ...$args);
    }
}