how to make verbose "equals" assertions in Behat with PHPUnit

behat_steps.php

<?php

$steps->Then('/^it should pass with:$/', function($world, $data) {
    try {
        assertEquals((string) $data, $world->output);
    } catch (\Exception $e) {
        $exceptionDiff = \PHPUnit_Framework_TestFailure::exceptionToString($e);
        throw new \Exception($exceptionDiff, $e->getCode(), $e);
    }
});