How to call parent class's method instead of overriden one from outside

Say I have these classes:

<?php
class Foo {
    function test( $s='' ) {
        return 'Foo test( '.$s.' )';
    }
}

class Bar extends Foo {
    function test( $s='' ) {
        return 'Bar test( '.$s.' )';
    }
}

$x = new Bar();
echo $x->test( 'hi' );

As expected, echo $x->test(); produces "Bar test( hi )"

Is there a shortcut to produce "Foo test( hi )" instead?

I tried things like echo $x->parent::test(); to no avail.

To be clear, I am aware I can add something like this inside Bar:

function callParent( $method ) {
    return parent::$method( ...array_slice( func_get_args(), 1 ) );
}

and then do this:

echo $x->callParent( 'test', 'hi' );

You can use reflection to call the parent's method implementation:

<?php

class Foo {
    function test( $s='' ) {
        return 'Foo test( '.$s.' )';
    }
}

class Bar extends Foo {
    function test( $s='' ) {
        return 'Bar test( '.$s.' )';
    }
}

$x = new Bar();

$reflection = new ReflectionObject($x);
$parent = $reflection->getParentClass();
$parentMethod = $parent->getMethod('test');

echo $parentMethod->invoke($x, 'hi');