dnspec5.php

<?php

/**
 * It is initializable'
 */
function ($calculator)
{
    $calculator->shouldHaveType('StringCalculator');
};

/**
 * It requires string input
 */
function ($calculator)
{
    $calculator->shouldThrow('\InvalidArgumentException')->during('add', [null]);
};

/**
 * It adds 2 numbers separated by comma
 */
function ($calculator)
{
    $calculator->add('1,2')->shouldReturn(3);
};