/** @test */
function a_customer_is_gold_if_they_have_the_respective_type()
{
$specification = new CustomerIsGold();
$goldCustomer = new Customer('gold');
$silverCustomer = new Customer('silver');
$this->assertTrue($specification->isSatisfiedBy($goldCustomer));
$this->assertFalse($specification->isSatisfiedBy($silverCustomer));
}
<?php
use App\Specification\Customer;
use App\Specification\CustomerIsGold;
require 'vendor/autoload.php';
$spec = new CustomerIsGold();
var_dump($spec->isSatisfiedBy(new Customer('gold')));