slack Send attachment to Slack

[Berocoder 14]

How can I add a large text-file as an attachment to a Slackpost? A working example would be great. I use SDriver https://github.com/andrea-magni/SDriver

 and the included demo works fine to send some strings.

What I did so far
https://gist.github.com/bero/e675bdf38c6e884be7e08377d6d52009