Easing in to RuboCop seems prudent, to keep making forward progress rather than just polishing incomplete code.

For me this meant passing the --only Lint option to RuboCop so only errors and warnings get flagged (for the time being).

In Atom the steps I took were:

• install atom.io/packages/…
• install atom.io/packages/…-rubocop

• tweaking the linter (via ~/.atom/config.cson)

  "linter-rubocop":
    command: "/Users/<name>/.rbenv/shims/rubocop --only Lint"
  

N.B. Replace /Users/<name> with the path to your home directory. I briefly tried using a relative path to the shim (~/.rbenv/shims/rubocop) but it broke Atom.