1 files changed, 168 insertions, 0 deletions
diff --git a/spec/tasks/rubocop_rake_spec.rb b/spec/tasks/rubocop_rake_spec.rb
new file mode 100644
index 00000000000..cf7e45aae28
--- /dev/null
+++ b/spec/tasks/rubocop_rake_spec.rb
@@ -0,0 +1,168 @@
+# frozen_string_literal: true
+# rubocop:disable RSpec/VerifiedDoubles
+
+require 'fast_spec_helper'
+require 'rake'
+require 'fileutils'
+
+require_relative '../support/silence_stdout'
+require_relative '../support/helpers/next_instance_of'
+require_relative '../support/helpers/rake_helpers'
+require_relative '../../rubocop/todo_dir'
+
+RSpec.describe 'rubocop rake tasks', :silence_stdout do
+  include RakeHelpers
+
+  before do
+    stub_const('Rails', double(:rails_env))
+    allow(Rails).to receive(:env).and_return(double(production?: false))
+
+    stub_const('ENV', ENV.to_hash.dup)
+
+    Rake.application.rake_require 'tasks/rubocop'
+  end
+
+  describe 'todo:generate', :aggregate_failures do
+    let(:tmp_dir) { Dir.mktmpdir }
+    let(:rubocop_todo_dir) { File.join(tmp_dir, '.rubocop_todo') }
+    let(:todo_dir) { RuboCop::TodoDir.new(rubocop_todo_dir) }
+
+    around do |example|
+      Dir.chdir(tmp_dir) do
+        with_inflections do
+          example.run
+        end
+      end
+    end
+
+    before do
+      allow(RuboCop::TodoDir).to receive(:new).and_return(todo_dir)
+
+      # This Ruby file will trigger the following 3 offenses.
+      File.write('a.rb', <<~RUBY)
+        a+b
+
+      RUBY
+
+      # Mimic GitLab's .rubocop_todo.yml avoids relying on RuboCop's
+      # default.yml configuration.
+      File.write('.rubocop.yml', <<~YAML)
+        <% unless ENV['REVEAL_RUBOCOP_TODO'] == '1' %>
+          <% Dir.glob('.rubocop_todo/**/*.yml').each do |rubocop_todo_yaml| %>
+        - '<%= rubocop_todo_yaml %>'
+          <% end %>
+        - '.rubocop_todo.yml'
+        <% end %>
+
+        AllCops:
+          NewCops: enable # Avoiding RuboCop warnings
+
+        Layout/SpaceAroundOperators:
+          Enabled: true
+
+        Layout/TrailingEmptyLines:
+          Enabled: true
+
+        Lint/Syntax:
+          Enabled: true
+
+        Style/FrozenStringLiteralComment:
+          Enabled: true
+      YAML
+
+      # Required to verify that we are revealing all TODOs via
+      # ENV['REVEAL_RUBOCOP_TODO'] = '1'.
+      # This file can be removed from specs after we've moved all offenses from
+      # .rubocop_todo.yml to .rubocop_todo/**/*.yml.
+      File.write('.rubocop_todo.yml', <<~YAML)
+        # Too many offenses
+        Layout/SpaceAroundOperators:
+          Enabled: false
+      YAML
+
+      # Previous offense now fixed.
+      todo_dir.write('Lint/Syntax', '')
+    end
+
+    after do
+      FileUtils.remove_entry(tmp_dir)
+    end
+
+    context 'without arguments' do
+      let(:run_task) { run_rake_task('rubocop:todo:generate') }
+
+      it 'generates TODOs for all RuboCop rules' do
+        expect { run_task }.to output(<<~OUTPUT).to_stdout
+          Generating RuboCop TODOs with:
+            rubocop --parallel --format RuboCop::Formatter::TodoFormatter
+
+          This might take a while...
+          Written to .rubocop_todo/layout/space_around_operators.yml
+          Written to .rubocop_todo/layout/trailing_empty_lines.yml
+          Written to .rubocop_todo/style/frozen_string_literal_comment.yml
+        OUTPUT
+
+        expect(rubocop_todo_dir_listing).to contain_exactly(
+          'layout/space_around_operators.yml',
+          'layout/trailing_empty_lines.yml',
+          'style/frozen_string_literal_comment.yml'
+        )
+      end
+
+      it 'sets acronyms for inflections' do
+        run_task
+
+        expect(ActiveSupport::Inflector.inflections.acronyms).to include(
+          'rspec' => 'RSpec',
+          'graphql' => 'GraphQL'
+        )
+      end
+    end
+
+    context 'with cop names as arguments' do
+      let(:run_task) do
+        cop_names = %w[
+          Style/FrozenStringLiteralComment Layout/TrailingEmptyLines
+          Lint/Syntax
+        ]
+
+        run_rake_task('rubocop:todo:generate', cop_names)
+      end
+
+      it 'generates TODOs for given RuboCop cops' do
+        expect { run_task }.to output(<<~OUTPUT).to_stdout
+          Generating RuboCop TODOs with:
+            rubocop --parallel --format RuboCop::Formatter::TodoFormatter --only Layout/TrailingEmptyLines,Lint/Syntax,Style/FrozenStringLiteralComment
+
+          This might take a while...
+          Written to .rubocop_todo/layout/trailing_empty_lines.yml
+          Written to .rubocop_todo/style/frozen_string_literal_comment.yml
+        OUTPUT
+
+        expect(rubocop_todo_dir_listing).to contain_exactly(
+          'layout/trailing_empty_lines.yml',
+          'style/frozen_string_literal_comment.yml'
+        )
+      end
+    end
+
+    private
+
+    def rubocop_todo_dir_listing
+      Dir.glob("#{rubocop_todo_dir}/**/*")
+        .select { |path| File.file?(path) }
+        .map { |path| path.delete_prefix("#{rubocop_todo_dir}/") }
+    end
+
+    def with_inflections
+      original = ActiveSupport::Inflector::Inflections.instance_variable_get(:@__instance__)[:en]
+      ActiveSupport::Inflector::Inflections.instance_variable_set(:@__instance__, en: original.dup)
+
+      yield
+    ensure
+      ActiveSupport::Inflector::Inflections.instance_variable_set(:@__instance__, en: original)
+    end
+  end
+end
+
+# rubocop:enable RSpec/VerifiedDoubles