Webmozart\Console\Util\StringUtil::parseString PHP Method

    public static function parseString($value, $nullable = true)
    {
        if ($nullable && (null === $value || 'null' === $value)) {
            return null;
        }
        if (null === $value) {
            return 'null';
        }
        if (true === $value) {
            return 'true';
        }
        if (false === $value) {
            return 'false';
        }
        return (string) $value;
    }

 /**
  * @dataProvider getParseStringTests
  */
 public function testParseString($input, $output, $nullable = true)
 {
     $this->assertSame($output, StringUtil::parseString($input, $nullable));
 }