According to the Rails guides (http://guides.rubyonrails.org/engines.html), after creating an engine using --mountable, there should should be a rake task in the parent app (not the engine), in the format
for copying engine migrations from the Rails engine into the parent app.
I’ve run through the tutorial in the guides twice and each time there is only the following rake task in the Rails engine (which copies the engine migrations into /test/dummy/db/migrate):
copies migrations from the Rails engine to the parent app.
Grateful for any help/suggestions you can offer.