CaracoleBundle/Solver/Config/UnitSolver.php

<?php

namespace Lc\CaracoleBundle\Solver\Config;

use Lc\CaracoleBundle\Model\Config\UnitInterface;

class UnitSolver
{
    public function getWeight(UnitInterface $unit, float $quantityProduct, ?float $quantity)
    {
        if ($quantity) {
            return ($quantityProduct / $unit->getCoefficient()) * $quantity;
        }
        else {
            return 0;
        }
    }
}