A big of a long-off goal with the indieweb BDD specs, would be for it to be a generic way to automate how many of the features of indieweb a site had implemented.  Kind of an automated IndieMark.  But really, just something to give you an idea of which features you could choose to implement, and which ones you’ve already implemented successfully.  It should of course be implementation agnostic – it’s just testing functionality after all (the point of BDD).
Why do BDD with my site?  It’s mostly as excuse to play around and learn about a few different things – indieweb, BDD, codeception.  I’m also a big fan of the BDD approach, forcing you to think about why you’re implementing something, what’s the value, before you go ahead and implement it.  Plus, regression tests FTW.
Started working on BDD specs for my site.  Using codeception – very impressed with it so far, quite a mature BDD tool.  After all the initial faffing around with setup, I’m at a point where I have a Gherkin spec that navigates to a page, checks for some content, and takes a screenshot.