src/Broadcast/Broadcast.php
public function preview($msgType, $message, $to, $by = self::PREVIEW_BY_OPENID)
    {
        $message = (new MessageBuilder())->msgType($msgType)->message($message)->to($to)->buildPreview($by);

        return $this->post(self::API_PREVIEW, $message);
    }
public function preview($msgType, $message, $to, $by = self::PREVIEW_BY_OPENID)
    {
        $message = (new MessageBuilder())->msgType($msgType)->message($message)->to($to)->buildPreview($by);

        return $this->post(self::API_PREVIEW, $message);
    }
Preview a message.

@param string $msgType message type
@param mixed  $message message
@param string $to
@param string $by

@return mixed