Rubocop: RuboCop suggests inherited extensions

[haines]

Expected behavior

RuboCop does not suggest to add extensions that have already been configured in an inherited gem.

Actual behavior

RuboCop suggests extensions that are already configured.

Steps to reproduce the problem

• set up a project that depends on rspec
• put inherit_gem in its .rubocop.yml, and inherit from a gem that depends on rubocop-rspec and has require: rubocop-rspec in its RuboCop config
• run RuboCop and receive an extension suggestion for rubocop-rspec

Minimal repro here: https://github.com/haines/rubocop-inherited-extensions-bug

$ git clone https://github.com/haines/rubocop-inherited-extensions-bug.git
$ cd rubocop-inherited-extensions-bug/project
$ bundle install
$ bundle exec rubocop
Inspecting 2 files
.C

Offenses:

spec/some_spec.rb:3:16: C: RSpec/DescribeClass: The first argument to describe should be the class or module being tested.
RSpec.describe 'offensive' do
               ^^^^^^^^^^^

2 files inspected, 1 offense detected

Tip: Based on detected gems, the following RuboCop extension libraries might be helpful:
  * rubocop-rspec (http://github.com/rubocop-hq/rubocop-rspec)

You can opt out of this message by adding the following to your config (see https://docs.rubocop.org/rubocop/extensions.html#extension-suggestions for more options):
  AllCops:
    SuggestExtensions: false

From the offense that's detected, it's clear that rubocop-rspec is configured, so the "Tip" shouldn't be displayed.

RuboCop version

$ bundle exec rubocop -V
1.5.1 (using Parser 2.7.2.0, rubocop-ast 1.3.0, running on ruby 2.7.2 x86_64-darwin19)
  - rubocop-rspec 2.0.1

[bbatsov]

Sounds like a task for @dvandersluis.

[dvandersluis]

Yeah it's not currently considering what's activated in rubocop.yml, just what's found from gems. I'll take a look!

[dvandersluis]

@haines In the meantime this configuration should work for you:

AllCops:
  SuggestExtensions:
    rubocop-rspec: false

[dvandersluis]

@haines can you confirm that rubocop-rspec is in your Gemfile.lock?

[haines]

@dvandersluis thanks for looking into this!

rubocop-rspec is in the Gemfile.lock: https://github.com/haines/rubocop-inherited-extensions-bug/blob/ace95f260920531df2f9a84d1e9ba39868611955/project/Gemfile.lock#L43

It's not in the Gemfile, though; it's a transitive dependency.