Alex\BehatLauncher\Behat\ProjectProperty::doMergeConfig PHP Method

    private function doMergeConfig(array $config, $value, $path)
    {
        if (false === ($pos = strpos($path, '.'))) {
            $config[$path] = $value;
            return $config;
        }
        $prefix = substr($path, 0, $pos);
        $suffix = substr($path, $pos + 1);
        if (!isset($config[$prefix])) {
            $config[$prefix] = $this->doMergeConfig(array(), $value, $suffix);
            return $config;
        }
        if (is_array($config[$prefix])) {
            $config[$prefix] = $this->doMergeConfig($config[$prefix], $value, $suffix);
            return $config;
        }
        throw new \RuntimeException(sprintf('Error at configuration key "%s": expected an array or empty, got "%s".', $prefix, $config[$prefix]));
    }