TestOutputCommand_Ask.php

<?php
$this->io->ask('What is your name?');

// default value:
$this->io->ask('Where are you from?', 'United States');

// validation:
$this->io->ask('Number of workers to start', 1, function ($number) {
    if (!is_numeric($number)) {
        throw new \RuntimeException('You must type a number.');
    }

    return (int) $number;
});