Bot for Friendica/ActivityPub

For running some tests on my test instances, I'd like to have a bot. I'd like a command line that can run on a cron job and which makes a post with some kind of dynamic text content, with the URL of the post on stdout. Ideally also:

• Have the post include an image
• Have the post be a reply to another post with a specified URL
• Option to wait for a new post from a specified user, with the post being a reply to that post
• Authentication via username/password passed on command line
• Nicer authentication options available

Does anyone have any experience with / recommendations for such a bot?