How to enable rubocop rails cops automatically?

Question

Is there a way to always enable rubocop rails cops via the config? I know I can run them via -R, but I'd like to make sure, that they are run when I just call rubocop alone.

Answer 1

Things have changed a bit since the last answer:

Rubocop team wanted to separate rails from the core of rubocop (which I think is great).
See this issue and this PR for more information.

So the new way of using Rails cops in Rubocop is by installing ruboco-rails gem.
Then in .rubocop.yml simply add:

require: rubocop-rails

Details here.

Enjoy!