Register policies directories for Rails 8 code statistics

[javierav]

This PR add a Rails::Railtie to Pundit for configure the new stats directories in upcomming Rails 8.

[Burgestrand]

Thanks, this is neat! I need to find the time to test this out.

[javierav]

@Burgestrand Can it be interesting to support older versions of rails? In such cases you would have to use a rake task (I never understood this ugly part of rails)

if Rails.version.to_f < 8.0
  rake_tasks do
    load "pundit/rails/tasks/pundit.rake"
  end
else
  initializer "pundit.stats_directories" do
    require "rails/code_statistics"

    if Rails.root.join("app/policies").directory?
      Rails::CodeStatistics.register_directory("Policies", "app/policies")
    end

    if Rails.root.join("test/policies").directory?
      Rails::CodeStatistics.register_directory("Policy tests", "test/policies", test_directory: true)
    end
  end
end

# pundit/rails/tasks/pundit.rake

task stats: "pundit:stats"

namespace :pundit do
  task :stats do
    require "rails/code_statistics"

    if Rails.root.join("app/policies").directory?
      ::STATS_DIRECTORIES << ["Policies",  "app/policies"]
    end

    if Rails.root.join("test/policies").directory?
      ::STATS_DIRECTORIES << ["Policy tests", "test/policies"]
      CodeStatistics::TEST_TYPES << "Policy tests"
    end
  end
end

I have also removed the RSpec part since rspec-rails gem is responsible for adding the tests to the statistics here

[Burgestrand]

@Burgestrand Can it be interesting to support older versions of rails? In such cases you would have to use a rake task (I never understood this ugly part of rails)

Gut feeling is "not really". I don't know how much you use rails stats, but for me it's probably less than once a year and it's not exactly an often-requested feature of Pundit 😄

This PR change is small enough and uses documented APIs, which makes me comfortable merging it. Whatever we merge we'll have to support for a relatively long time.