Laravel\Lumen\Testing\CrawlerTrait::transformHeadersToServerVars PHP Method

    protected function transformHeadersToServerVars(array $headers)
    {
        $server = [];
        $prefix = 'HTTP_';
        foreach ($headers as $name => $value) {
            $name = strtr(strtoupper($name), '-', '_');
            if (!starts_with($name, $prefix) && $name != 'CONTENT_TYPE') {
                $name = $prefix . $name;
            }
            $server[$name] = $value;
        }
        return $server;
    }