Add RuboCop RSpec support

[pirj]

What is the purpose of this pull request?

Previously, RuboCop RSpec failed to detect RSpec aliases. A number of cops were failing false offences, and some cops were unable to lint, as they were skipping locally defined RSpec aliases taking them for arbitrary blocks and method calls.

See:

• Add docs and provide a reference implementation on RSpec DSL aliases configuration in third-party gems rubocop/rubocop-rspec#1077
• RSpec aliases runtime matchers rubocop/rubocop-rspec#956
• Make RSpec describe_rule DRY #103

Example project:

Gemfile:

# frozen_string_literal: true

source 'https://rubygems.org'

gem 'action_policy', path: '../../action_policy'
gem 'rubocop-rspec'

.rubocop.yml:

AllCops:
  NewCops: enable

require:
  - rubocop-rspec

inherit_gem:
  action_policy: .rubocop-rspec-aliases.yml

spec/policies/a_policy_spec.rb:

# frozen_string_literal: true

RSpec.describe 'A' do
  describe_rule :luck? do
    succeed 'when stars align'
  end
end

Before

$ rubocop
Inspecting 2 files
.C

Offenses:

spec/policies/a_policy_spec.rb:3:1: C: RSpec/EmptyExampleGroup: Empty example group detected.
RSpec.describe 'A' do
^^^^^^^^^^^^^^^^^^

2 files inspected, 1 offense detected

After

$ rubocop
Inspecting 2 files
..

2 files inspected, no offenses detected

What changes did you make? (overview)

• added an RSpec alias config file that RuboCop is able to load and append to the default RuboCop RSpec alias configuration.
• added docs on how to tell RuboCop to use those aliases

Is there anything you'd like reviewers to focus on?

I don't have any real projects using Action Policy handy. Please test this change on a real project.

Should I through in some spec that uses describe_rule/succeed/... aliases so that Lint Ruby build job checked them with rubocop-rspec and made sure there are no offences?

---

PR checklist:

• [-] Tests included
• Documentation updated
• Changelog entry added

[palkan]

Awesome! Thanks!

Just one request: let's move the config file into the config/rubocop-rspec.yml or anything else, just not the project's root folder.

[pirj]

Sounds good, will move in both PRs 👍

[pirj]

Moved the config and tested again, works.

[palkan]

Thanks!