test.php

<?php
$options = [
  'memory_cost' => 1<<17, // 128 Mb
  'time_cost'   => 4,
  'threads'     => 2,
  ];
$test_hash = password_hash('foobar', PASSWORD_ARGON2I, $options);
if(!password_verify('foobar', $test_hash)) {
	echo("ARGON2I seems to not be working properly...\n");
} else {
	echo("ARGON2I is fine so far...\n");
}