gist.php

<?php
protected function interact(InputInterface $input, OutputInterface $output)
{
    $dialog    = $this->getDialogHelper();
    $validator = Validation::createValidator();

    $inputValue = $dialog->askAndValidate($output, 'Enter some input: ', function($value) use($validator){
        $errors = $validator->validateValue($value, new Assert\NotBlank());
        if (count($errors)) {
            throw new \InvalidArgumentException((string) $errors);
        }

        return $value;
    });

    $MoreInputValue = $dialog->askAndValidate($output, 'Enter even more input input: ', function($value) use($validator){
        $errors = $validator->validateValue($value, new Assert\NotBlank());
        if (count($errors)) {
            throw new \InvalidArgumentException((string) $errors);
        }

        return $value;
    });
}