gistfile1.txt

<?php

require_once "vendor/autoload.php";

use Symfony\Component\Config;
use Symfony\Component\Config\Definition\ConfigurationInterface;
use Symfony\Component\Yaml\Yaml;

class MyConfig implements ConfigurationInterface
{

    public function getConfigTreeBuilder()
    {
        $treeBuilder = new Config\Definition\Builder\TreeBuilder();
        $rootNode = $treeBuilder->root('config');

        $rootNode
            ->children()
                ->booleanNode('use_mock')
                    ->isRequired()
                    ->cannotBeEmpty()
                ->end()
                ->scalarNode('foo')
                ->end()
            ->end()
        ;

        return $treeBuilder;
    }
}

$yamlValues = Yaml::parse(file_get_contents('test.yml'));

$processor = new Config\Definition\Processor();
$config = $processor->processConfiguration(new MyConfig(), $yamlValues);

// Throws:
//   PHP Fatal error:  Uncaught exception 'Symfony\Component\Config\Definition\Exception\InvalidConfigurationException' with
//   message 'The path "config.use_mock" cannot contain an empty value, but got false.' in
//   .../vendor/symfony/config/Symfony/Component/Config/Definition/VariableNode.php:88

var_dump($config);




/** test.yml:

 * config:
    use_mock: false
    foo: bar

 */