public function render()
    {
        $process = $this->getProcess();
        $process->run();
        if (0 === $process->getExitCode()) {
            return file_get_contents($this->getOutput());
        }

        throw new \RuntimeException(
            sprintf('Unable to render PDF. Command "%s" exited with "%s" (code: %s): %s',
                $process->getCommandLine(),
                $process->getExitCodeText(),
                $process->getExitCode(),
                $process->getErrorOutput()
            )
        );
    }