Merge branch '284596-introduce-static-analysis-check-for-feature-flag-usage' into 'master'

Introduce a new Gitlab/MarkUsedFeatureFlags cop

See merge request gitlab-org/gitlab!61052

.gitlab/ci/rails.gitlab-ci.yml

@@ -47,7 +47,6 @@
       - rspec_profiling/
       - tmp/capybara/
       - tmp/memory_test/
-      - tmp/feature_flags/
       - log/*.log
     reports:
       junit: junit_rspec.xml
@@ -222,6 +221,11 @@ static-analysis:
   script:
     - run_timed_command "retry yarn install --frozen-lockfile"
     - scripts/static-analysis
+  artifacts:
+    expire_in: 31d
+    when: always
+    paths:
+      - tmp/feature_flags/
 
 static-analysis as-if-foss:
   extends:
@@ -460,23 +464,11 @@ rspec:coverage:
 rspec:feature-flags:
   extends:
     - .coverage-base
-    - .rails:rules:rspec-feature-flags
+    - .static-analysis:rules:ee-and-foss
   stage: post-test
-  # We cannot use needs since it would mean needing 84 jobs (since most are parallelized)
-  # so we use `dependencies` here.
-  dependencies:
+  needs:
     - setup-test-env
-    - rspec migration pg12
-    - rspec unit pg12
-    - rspec integration pg12
-    - rspec system pg12
-    - rspec-ee migration pg12
-    - rspec-ee unit pg12
-    - rspec-ee integration pg12
-    - rspec-ee system pg12
-    - rspec-ee unit pg12 geo
-    - rspec-ee integration pg12 geo
-    - rspec-ee system pg12 geo
+    - static-analysis
     - memory-static
     - memory-on-boot
   script:

.gitlab/ci/rules.gitlab-ci.yml

@@ -932,14 +932,6 @@
     - <<: *if-merge-request-title-run-all-rspec
       when: always
 
-.rails:rules:rspec-feature-flags:
-  rules:
-    - <<: *if-not-ee
-      when: never
-    - <<: *if-default-branch-schedule-2-hourly
-      allow_failure: true
-    - <<: *if-merge-request-title-run-all-rspec
-
 .rails:rules:default-branch-schedule-nightly--code-backstage:
   rules:
     - <<: *if-default-branch-schedule-nightly

app/controllers/projects/issues_controller.rb

@@ -49,10 +49,9 @@ class Projects::IssuesController < Projects::ApplicationController
   end
 
   before_action only: :show do
-    real_time_feature_flag = :real_time_issue_sidebar
-    real_time_enabled = Gitlab::ActionCable::Config.in_app? || Feature.enabled?(real_time_feature_flag, @project)
+    real_time_enabled = Gitlab::ActionCable::Config.in_app? || Feature.enabled?(:real_time_issue_sidebar, @project)
 
-    push_to_gon_attributes(:features, real_time_feature_flag, real_time_enabled)
+    push_to_gon_attributes(:features, :real_time_issue_sidebar, real_time_enabled)
     push_frontend_feature_flag(:confidential_notes, @project, default_enabled: :yaml)
     push_frontend_feature_flag(:issue_assignees_widget, @project, default_enabled: :yaml)
     push_frontend_feature_flag(:labels_widget, @project, default_enabled: :yaml)

ee/app/views/layouts/nav/sidebar/_group_trial_status_widget.html.haml

@@ -3,9 +3,8 @@
 - return unless show_trial_status_widget?(root_group)
 
 -# For the current Growth::Conversion experiment
-- experiment_key = :show_trial_status_in_sidebar
-- record_experiment_group(experiment_key, root_group)
-- return unless experiment_enabled?(experiment_key, subject: root_group)
+- record_experiment_group(:show_trial_status_in_sidebar, root_group)
+- return unless experiment_enabled?(:show_trial_status_in_sidebar, subject: root_group)
 
 = nav_link do
   #js-trial-status-widget{ data: trial_status_widget_data_attrs(root_group) }

rubocop/code_reuse_helpers.rb

@@ -32,59 +32,79 @@ module RuboCop
 
     # Returns true if the given node resides in app/finders or ee/app/finders.
     def in_finder?(node)
-      in_directory?(node, 'finders')
+      in_app_directory?(node, 'finders')
     end
 
     # Returns true if the given node resides in app/models or ee/app/models.
     def in_model?(node)
-      in_directory?(node, 'models')
+      in_app_directory?(node, 'models')
     end
 
     # Returns true if the given node resides in app/services or ee/app/services.
     def in_service_class?(node)
-      in_directory?(node, 'services')
+      in_app_directory?(node, 'services')
     end
 
     # Returns true if the given node resides in app/presenters or
     # ee/app/presenters.
     def in_presenter?(node)
-      in_directory?(node, 'presenters')
+      in_app_directory?(node, 'presenters')
     end
 
     # Returns true if the given node resides in app/serializers or
     # ee/app/serializers.
     def in_serializer?(node)
-      in_directory?(node, 'serializers')
+      in_app_directory?(node, 'serializers')
     end
 
     # Returns true if the given node resides in app/workers or ee/app/workers.
     def in_worker?(node)
-      in_directory?(node, 'workers')
+      in_app_directory?(node, 'workers')
     end
 
     # Returns true if the given node resides in app/controllers or
     # ee/app/controllers.
     def in_controller?(node)
-      in_directory?(node, 'controllers')
+      in_app_directory?(node, 'controllers')
+    end
+
+    # Returns true if the given node resides in app/graphql/types,
+    # ee/app/graphql/types, or ee/app/graphql/ee/types.
+    def in_graphql_types?(node)
+      in_app_directory?(node, 'graphql/types') || in_app_directory?(node, 'graphql/ee/types')
     end
 
     # Returns true if the given node resides in lib/api or ee/lib/api.
     def in_api?(node)
+      in_lib_directory?(node, 'api')
+    end
+
+    # Returns true if the given node resides in spec or ee/spec.
+    def in_spec?(node)
       file_path_for_node(node).start_with?(
-        File.join(ce_lib_directory, 'api'),
-        File.join(ee_lib_directory, 'api')
+        ce_spec_directory,
+        ee_spec_directory
       )
     end
 
     # Returns `true` if the given AST node resides in the given directory,
     # relative to app and/or ee/app.
-    def in_directory?(node, directory)
+    def in_app_directory?(node, directory)
       file_path_for_node(node).start_with?(
         File.join(ce_app_directory, directory),
         File.join(ee_app_directory, directory)
       )
     end
 
+    # Returns `true` if the given AST node resides in the given directory,
+    # relative to lib and/or ee/lib.
+    def in_lib_directory?(node, directory)
+      file_path_for_node(node).start_with?(
+        File.join(ce_lib_directory, directory),
+        File.join(ee_lib_directory, directory)
+      )
+    end
+
     # Returns the receiver name of a send node.
     #
     # For the AST node `(send (const nil? :Foo) ...)` this would return
@@ -149,6 +169,14 @@ module RuboCop
       File.join(rails_root, 'ee', 'lib')
     end
 
+    def ce_spec_directory
+      File.join(rails_root, 'spec')
+    end
+
+    def ee_spec_directory
+      File.join(rails_root, 'ee', 'spec')
+    end
+
     def rails_root
       File.expand_path('..', __dir__)
     end

rubocop/cop/gitlab/mark_used_feature_flags.rb

+# frozen_string_literal: true
+
+require_relative '../../code_reuse_helpers'
+
+module RuboCop
+  module Cop
+    module Gitlab
+      # This cop tracks the usage of feature flags among the codebase.
+      #
+      # The files set in `tmp/feature_flags/*.used` can then be used for verification purpose.
+      #
+      class MarkUsedFeatureFlags < RuboCop::Cop::Cop
+        include RuboCop::CodeReuseHelpers
+
+        FEATURE_METHODS = %i[enabled? disabled?].freeze
+        EXPERIMENTATION_METHODS = %i[active?].freeze
+        EXPERIMENT_METHODS = %i[
+          experiment
+          experiment_enabled?
+          push_frontend_experiment
+        ].freeze
+        RUGGED_METHODS = %i[
+          use_rugged?
+        ].freeze
+        WORKER_METHODS = %i[
+          data_consistency
+        ].freeze
+        GRAPHQL_METHODS = %i[
+          field
+        ].freeze
+        SELF_METHODS = %i[
+          push_frontend_feature_flag
+          limit_feature_flag=
+        ].freeze + EXPERIMENT_METHODS + RUGGED_METHODS + WORKER_METHODS
+
+        RESTRICT_ON_SEND = FEATURE_METHODS + EXPERIMENTATION_METHODS + GRAPHQL_METHODS + SELF_METHODS
+
+        USAGE_DATA_COUNTERS_EVENTS_YAML_GLOBS = [
+          File.expand_path("../../../config/metrics/aggregates/*.yml", __dir__),
+          File.expand_path("../../../lib/gitlab/usage_data_counters/known_events/*.yml", __dir__)
+        ].freeze
+
+        DYNAMIC_FEATURE_FLAGS = [
+          :usage_data_static_site_editor_commits, # https://gitlab.com/gitlab-org/gitlab/-/issues/284082
+          :usage_data_static_site_editor_merge_requests # https://gitlab.com/gitlab-org/gitlab/-/issues/284083
+        ].freeze
+
+        # Called before all on_... have been called
+        # When refining this method, always call `super`
+        def on_new_investigation
+          super
+          track_dynamic_feature_flags!
+          track_usage_data_counters_known_events!
+        end
+
+        def on_casgn(node)
+          _, lhs_name, rhs = *node
+
+          save_used_feature_flag(rhs.value) if lhs_name == :FEATURE_FLAG
+        end
+
+        def on_send(node)
+          return if in_spec?(node)
+          return unless trackable_flag?(node)
+
+          flag_arg = flag_arg(node)
+          flag_value = flag_value(node)
+          return unless flag_value
+
+          if flag_arg_is_str_or_sym?(node)
+            if caller_is_feature_gitaly?(node)
+              save_used_feature_flag("gitaly_#{flag_value}")
+            else
+              save_used_feature_flag(flag_value)
+            end
+
+            if experiment_method?(node) || experimentation_method?(node)
+              # Additionally, mark experiment-related feature flag as used as well
+              matching_feature_flags = defined_feature_flags.select { |flag| flag == "#{flag_value}_experiment_percentage" }
+              matching_feature_flags.each do |matching_feature_flag|
+                puts_if_ci(node, "The '#{matching_feature_flag}' feature flag tracks the #{flag_value} experiment, which is still in use, so we'll mark it as used.")
+                save_used_feature_flag(matching_feature_flag)
+              end
+            end
+          elsif flag_arg_is_send_type?(node)
+            puts_if_ci(node, "Feature flag is dynamic: '#{flag_value}.")
+          elsif flag_arg_is_dstr_or_dsym?(node)
+            str_prefix = flag_arg.children[0]
+            rest_children = flag_arg.children[1..]
+
+            if rest_children.none? { |child| child.str_type? }
+              matching_feature_flags = defined_feature_flags.select { |flag| flag.start_with?(str_prefix.value) }
+              matching_feature_flags.each do |matching_feature_flag|
+                puts_if_ci(node, "The '#{matching_feature_flag}' feature flag starts with '#{str_prefix.value}', so we'll optimistically mark it as used.")
+                save_used_feature_flag(matching_feature_flag)
+              end
+            else
+              puts_if_ci(node, "Interpolated feature flag name has multiple static string parts, we won't track it.")
+            end
+          else
+            puts_if_ci(node, "Feature flag has an unknown type: #{flag_arg.type}.")
+          end
+        end
+
+        private
+
+        def puts_if_ci(node, text)
+          puts "#{text} (call: `#{node.source}`, source: #{node.location.expression.source_buffer.name})" if ENV['CI']
+        end
+
+        def save_used_feature_flag(feature_flag_name)
+          used_feature_flag_file = File.expand_path("../../../tmp/feature_flags/#{feature_flag_name}.used", __dir__)
+          return if File.exist?(used_feature_flag_file)
+
+          FileUtils.touch(used_feature_flag_file)
+        end
+
+        def class_caller(node)
+          node.children[0]&.const_name.to_s
+        end
+
+        def method_name(node)
+          node.children[1]
+        end
+
+        def flag_arg(node)
+          if worker_method?(node)
+            return unless node.children.size > 3
+
+            node.children[3].each_pair.find do |pair|
+              pair.key.value == :feature_flag
+            end&.value
+          elsif graphql_method?(node)
+            return unless node.children.size > 3
+
+            opts_index = node.children[3].hash_type? ? 3 : 4
+            return unless node.children[opts_index]
+
+            node.children[opts_index].each_pair.find do |pair|
+              pair.key.value == :feature_flag
+            end&.value
+          else
+            arg_index = rugged_method?(node) ? 3 : 2
+
+            node.children[arg_index]
+          end
+        end
+
+        def flag_value(node)
+          flag_arg = flag_arg(node)
+          return unless flag_arg
+
+          if flag_arg.respond_to?(:value)
+            flag_arg.value
+          else
+            flag_arg
+          end.to_s.tr("\n/", ' _')
+        end
+
+        def flag_arg_is_str_or_sym?(node)
+          flag_arg = flag_arg(node)
+          flag_arg.str_type? || flag_arg.sym_type?
+        end
+
+        def flag_arg_is_send_type?(node)
+          flag_arg(node).send_type?
+        end
+
+        def flag_arg_is_dstr_or_dsym?(node)
+          flag = flag_arg(node)
+          (flag.dstr_type? || flag.dsym_type?) && flag.children[0].str_type?
+        end
+
+        def caller_is_feature?(node)
+          class_caller(node) == "Feature"
+        end
+
+        def caller_is_feature_gitaly?(node)
+          class_caller(node) == "Feature::Gitaly"
+        end
+
+        def caller_is_experimentation?(node)
+          class_caller(node) == "Gitlab::Experimentation"
+        end
+
+        def experiment_method?(node)
+          EXPERIMENT_METHODS.include?(method_name(node))
+        end
+
+        def rugged_method?(node)
+          RUGGED_METHODS.include?(method_name(node))
+        end
+
+        def feature_method?(node)
+          FEATURE_METHODS.include?(method_name(node)) && (caller_is_feature?(node) || caller_is_feature_gitaly?(node))
+        end
+
+        def experimentation_method?(node)
+          EXPERIMENTATION_METHODS.include?(method_name(node)) && caller_is_experimentation?(node)
+        end
+
+        def worker_method?(node)
+          WORKER_METHODS.include?(method_name(node))
+        end
+
+        def graphql_method?(node)
+          GRAPHQL_METHODS.include?(method_name(node)) && in_graphql_types?(node)
+        end
+
+        def self_method?(node)
+          SELF_METHODS.include?(method_name(node)) && class_caller(node).empty?
+        end
+
+        def trackable_flag?(node)
+          feature_method?(node) || experimentation_method?(node) || graphql_method?(node) || self_method?(node)
+        end
+
+        # Marking all event's feature flags as used as Gitlab::UsageDataCounters::HLLRedisCounter.track_event{,context}
+        # is mostly used with dynamic event name.
+        def track_dynamic_feature_flags!
+          DYNAMIC_FEATURE_FLAGS.each(&method(:save_used_feature_flag))
+        end
+
+        # Marking all event's feature flags as used as Gitlab::UsageDataCounters::HLLRedisCounter.track_event{,context}
+        # is mostly used with dynamic event name.
+        def track_usage_data_counters_known_events!
+          usage_data_counters_known_event_feature_flags.each(&method(:save_used_feature_flag))
+        end
+
+        def usage_data_counters_known_event_feature_flags
+          USAGE_DATA_COUNTERS_EVENTS_YAML_GLOBS.each_with_object(Set.new) do |glob, memo|
+            Dir.glob(glob).each do |path|
+              YAML.safe_load(File.read(path))&.each do |hash|
+                memo << hash['feature_flag'] if hash['feature_flag']
+              end
+            end
+          end
+        end
+
+        def defined_feature_flags
+          @defined_feature_flags ||= begin
+            flags_paths = [
+              'config/feature_flags/**/*.yml'
+            ]
+
+            # For EE additionally process `ee/` feature flags
+            if File.exist?(File.expand_path('../../../ee/app/models/license.rb', __dir__)) && !%w[true 1].include?(ENV['FOSS_ONLY'].to_s)
+              flags_paths << 'ee/config/feature_flags/**/*.yml'
+            end
+
+            flags_paths.each_with_object([]) do |flags_path, memo|
+              flags_path = File.expand_path("../../../#{flags_path}", __dir__)
+              Dir.glob(flags_path).each do |path|
+                feature_flag_name = File.basename(path, '.yml')
+
+                memo << feature_flag_name
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end

scripts/used-feature-flags

@@ -28,6 +28,16 @@ flags_paths = [
 # For EE additionally process `ee/` feature flags
 if File.exist?('ee/app/models/license.rb') && !%w[true 1].include?(ENV['FOSS_ONLY'].to_s)
   flags_paths << 'ee/config/feature_flags/**/*.yml'
+
+  # Geo feature flags are constructed dynamically and there's no explicit checks in the codebase so we mark all
+  # the replicators' derived feature flags as used.
+  # See https://gitlab.com/gitlab-org/gitlab/-/blob/54e802e8fe76b6f93656d75ef9b566bf57b60f41/ee/lib/gitlab/geo/replicator.rb#L183-185
+  Dir.glob('ee/app/replicators/geo/*_replicator.rb').each_with_object(Set.new) do |path, memo|
+    replicator_name = File.basename(path, '.rb')
+    feature_flag_name = "geo_#{replicator_name.delete_suffix('_replicator')}_replication"
+
+    FileUtils.touch(File.join('tmp', 'feature_flags', "#{feature_flag_name}.used"))
+  end
 end
 
 all_flags = {}
@@ -41,7 +51,17 @@ flags_paths.each do |flags_path|
     feature_flag_name = File.basename(path, '.yml')
 
     # TODO: we need a better way of tracking use of Gitaly FF across Gitaly and GitLab
-    next if feature_flag_name.start_with?('gitaly_')
+    if feature_flag_name.start_with?('gitaly_')
+      puts "Skipping the #{feature_flag_name} feature flag since it starts with 'gitaly_'."
+      next
+    end
+
+    # Dynamic feature flag names for redirect to latest CI templates
+    # See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/63144/diffs#fa2193ace3f6a02f7ef9995ef9bc519eca92c4ee_57_84
+    if feature_flag_name.start_with?('redirect_to_latest_template_')
+      puts "Skipping the #{feature_flag_name} feature flag since it starts with 'redirect_to_latest_template_'."
+      next
+    end
 
     all_flags[feature_flag_name] = File.exist?(File.join('tmp', 'feature_flags', feature_flag_name + '.used'))
   end

spec/experiments/application_experiment_spec.rb

@@ -19,12 +19,6 @@ RSpec.describe ApplicationExperiment, :experiment do
     allow(subject).to receive(:enabled?).and_return(true)
   end
 
-  it "naively assumes a 1x1 relationship to feature flags for tests" do
-    expect(Feature).to receive(:persist_used!).with('namespaced_stub')
-
-    described_class.new('namespaced/stub')
-  end
-
   it "doesn't raise an exception without a defined control" do
     # because we have a default behavior defined
 

spec/fast_spec_helper.rb

@@ -22,3 +22,8 @@ ActiveSupport::Dependencies.autoload_paths << 'lib'
 ActiveSupport::Dependencies.autoload_paths << 'ee/lib'
 
 ActiveSupport::XmlMini.backend = 'Nokogiri'
+
+RSpec.configure do |config|
+  config.filter_run focus: true
+  config.run_all_when_everything_filtered = true
+end

spec/rubocop/code_reuse_helpers_spec.rb

@@ -150,6 +150,31 @@ RSpec.describe RuboCop::CodeReuseHelpers do
     end
   end
 
+  describe '#in_graphql_types?' do
+    %w[
+      app/graphql/types
+      ee/app/graphql/ee/types
+      ee/app/graphql/types
+    ].each do |path|
+      it "returns true for a node in #{path}" do
+        node = build_and_parse_source('10', rails_root_join(path, 'foo.rb'))
+
+        expect(cop.in_graphql_types?(node)).to eq(true)
+      end
+    end
+
+    %w[
+      app/graphql/resolvers
+      app/foo
+    ].each do |path|
+      it "returns true for a node in #{path}" do
+        node = build_and_parse_source('10', rails_root_join(path, 'foo.rb'))
+
+        expect(cop.in_graphql_types?(node)).to eq(false)
+      end
+    end
+  end
+
   describe '#in_api?' do
     it 'returns true for a node in the API directory' do
       node = build_and_parse_source('10', rails_root_join('lib', 'api', 'foo.rb'))
@@ -164,25 +189,67 @@ RSpec.describe RuboCop::CodeReuseHelpers do
     end
   end
 
-  describe '#in_directory?' do
+  describe '#in_spec?' do
+    it 'returns true for a node in the spec directory' do
+      node = build_and_parse_source('10', rails_root_join('spec', 'foo.rb'))
+
+      expect(cop.in_spec?(node)).to eq(true)
+    end
+
+    it 'returns true for a node in the ee/spec directory' do
+      node = build_and_parse_source('10', rails_root_join('ee', 'spec', 'foo.rb'))
+
+      expect(cop.in_spec?(node)).to eq(true)
+    end
+
+    it 'returns false for a node outside the spec directory' do
+      node = build_and_parse_source('10', rails_root_join('lib', 'foo.rb'))
+
+      expect(cop.in_spec?(node)).to eq(false)
+    end
+  end
+
+  describe '#in_app_directory?' do
     it 'returns true for a directory in the CE app/ directory' do
       node = build_and_parse_source('10', rails_root_join('app', 'models', 'foo.rb'))
 
-      expect(cop.in_directory?(node, 'models')).to eq(true)
+      expect(cop.in_app_directory?(node, 'models')).to eq(true)
     end
 
     it 'returns true for a directory in the EE app/ directory' do
       node =
         build_and_parse_source('10', rails_root_join('ee', 'app', 'models', 'foo.rb'))
 
-      expect(cop.in_directory?(node, 'models')).to eq(true)
+      expect(cop.in_app_directory?(node, 'models')).to eq(true)
     end
 
     it 'returns false for a directory in the lib/ directory' do
       node =
         build_and_parse_source('10', rails_root_join('lib', 'models', 'foo.rb'))
 
-      expect(cop.in_directory?(node, 'models')).to eq(false)
+      expect(cop.in_app_directory?(node, 'models')).to eq(false)
+    end
+  end
+
+  describe '#in_lib_directory?' do
+    it 'returns true for a directory in the CE lib/ directory' do
+      node = build_and_parse_source('10', rails_root_join('lib', 'models', 'foo.rb'))
+
+      expect(cop.in_lib_directory?(node, 'models')).to eq(true)
+    end
+
+    it 'returns true for a directory in the EE lib/ directory' do
+      node =
+        build_and_parse_source('10', rails_root_join('ee', 'lib', 'models', 'foo.rb'))
+
+      expect(cop.in_lib_directory?(node, 'models')).to eq(true)
+    end
+
+    it 'returns false for a directory in the app/ directory' do
+      node =
+        build_and_parse_source('10', rails_root_join('app', 'models', 'foo.rb'))
+
+      expect(cop.in_lib_directory?(node, 'models')).to eq(false)
     end
   end
 

spec/rubocop/cop/gitlab/mark_used_feature_flags_spec.rb

+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+require 'rubocop'
+require 'rubocop/rspec/support'
+require_relative '../../../../rubocop/cop/gitlab/mark_used_feature_flags'
+
+RSpec.describe RuboCop::Cop::Gitlab::MarkUsedFeatureFlags do
+  let(:defined_feature_flags) do
+    %w[a_feature_flag foo_hello foo_world baz_experiment_percentage bar_baz]
+  end
+
+  subject(:cop) { described_class.new }
+
+  before do
+    stub_const("#{described_class}::DYNAMIC_FEATURE_FLAGS", [])
+    allow(cop).to receive(:defined_feature_flags).and_return(defined_feature_flags)
+    allow(cop).to receive(:usage_data_counters_known_event_feature_flags).and_return([])
+  end
+
+  def feature_flag_path(feature_flag_name)
+    File.expand_path("../../../../tmp/feature_flags/#{feature_flag_name}.used", __dir__)
+  end
+
+  shared_examples 'sets flag as used' do |method_call, flags_to_be_set|
+    it 'sets the flag as used' do
+      Array(flags_to_be_set).each do |flag_to_be_set|
+        expect(FileUtils).to receive(:touch).with(feature_flag_path(flag_to_be_set))
+      end
+
+      expect_no_offenses(<<~RUBY)
+        class Foo < ApplicationRecord
+          #{method_call}
+        end
+      RUBY
+    end
+  end
+
+  shared_examples 'does not set any flags as used' do |method_call|
+    it 'sets the flag as used' do
+      expect(FileUtils).not_to receive(:touch)
+
+      expect_no_offenses(method_call)
+    end
+  end
+
+  %w[
+    Feature.enabled?
+    Feature.disabled?
+    push_frontend_feature_flag
+  ].each do |feature_flag_method|
+    context "#{feature_flag_method} method" do
+      context 'a string feature flag' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}("foo")|, 'foo'
+      end
+
+      context 'a symbol feature flag' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(:foo)|, 'foo'
+      end
+
+      context 'an interpolated string feature flag with a string prefix' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}("foo_\#{bar}")|, %w[foo_hello foo_world]
+      end
+
+      context 'an interpolated symbol feature flag with a string prefix' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(:"foo_\#{bar}")|, %w[foo_hello foo_world]
+      end
+
+      context 'a string with a "/" in it' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}("bar/baz")|, 'bar_baz'
+      end
+
+      context 'an interpolated string feature flag with a string prefix and suffix' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(:"foo_\#{bar}_baz")|
+      end
+
+      context 'a dynamic string feature flag as a variable' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(a_variable, an_arg)|
+      end
+
+      context 'an integer feature flag' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(123)|
+      end
+    end
+  end
+
+  %w[
+    Feature::Gitaly.enabled?
+    Feature::Gitaly.disabled?
+  ].each do |feature_flag_method|
+    context "#{feature_flag_method} method" do
+      context 'a string feature flag' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}("foo")|, 'gitaly_foo'
+      end
+
+      context 'a symbol feature flag' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(:foo)|, 'gitaly_foo'
+      end
+
+      context 'an interpolated string feature flag with a string prefix' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}("foo_\#{bar}")|, %w[foo_hello foo_world]
+      end
+
+      context 'an interpolated symbol feature flag with a string prefix' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(:"foo_\#{bar}")|, %w[foo_hello foo_world]
+      end
+
+      context 'an interpolated string feature flag with a string prefix and suffix' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(:"foo_\#{bar}_baz")|
+      end
+
+      context 'a dynamic string feature flag as a variable' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(a_variable, an_arg)|
+      end
+
+      context 'an integer feature flag' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(123)|
+      end
+    end
+  end
+
+  %w[
+    experiment
+    experiment_enabled?
+    push_frontend_experiment
+    Gitlab::Experimentation.active?
+  ].each do |feature_flag_method|
+    context "#{feature_flag_method} method" do
+      context 'a string feature flag' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}("baz")|, %w[baz baz_experiment_percentage]
+      end
+
+      context 'a symbol feature flag' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(:baz)|, %w[baz baz_experiment_percentage]
+      end
+
+      context 'an interpolated string feature flag with a string prefix' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}("foo_\#{bar}")|, %w[foo_hello foo_world]
+      end
+
+      context 'an interpolated symbol feature flag with a string prefix' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(:"foo_\#{bar}")|, %w[foo_hello foo_world]
+      end
+
+      context 'an interpolated string feature flag with a string prefix and suffix' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(:"foo_\#{bar}_baz")|
+      end
+
+      context 'a dynamic string feature flag as a variable' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(a_variable, an_arg)|
+      end
+
+      context 'an integer feature flag' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(123)|
+      end
+    end
+  end
+
+  %w[
+    use_rugged?
+  ].each do |feature_flag_method|
+    context "#{feature_flag_method} method" do
+      context 'a string feature flag' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(arg, "baz")|, 'baz'
+      end
+
+      context 'a symbol feature flag' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(arg, :baz)|, 'baz'
+      end
+
+      context 'an interpolated string feature flag with a string prefix' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(arg, "foo_\#{bar}")|, %w[foo_hello foo_world]
+      end
+
+      context 'an interpolated symbol feature flag with a string prefix' do
+        include_examples 'sets flag as used', %Q|#{feature_flag_method}(arg, :"foo_\#{bar}")|, %w[foo_hello foo_world]
+      end
+
+      context 'an interpolated string feature flag with a string prefix and suffix' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(arg, :"foo_\#{bar}_baz")|
+      end
+
+      context 'a dynamic string feature flag as a variable' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(a_variable, an_arg)|
+      end
+
+      context 'an integer feature flag' do
+        include_examples 'does not set any flags as used', %Q|#{feature_flag_method}(arg, 123)|
+      end
+    end
+  end
+
+  describe 'self.limit_feature_flag = :foo' do
+    include_examples 'sets flag as used', 'self.limit_feature_flag = :foo', 'foo'
+  end
+
+  describe 'FEATURE_FLAG = :foo' do
+    include_examples 'sets flag as used', 'FEATURE_FLAG = :foo', 'foo'
+  end
+
+  describe 'Worker `data_consistency` method' do
+    include_examples 'sets flag as used', 'data_consistency :delayed, feature_flag: :foo', 'foo'
+    include_examples 'does not set any flags as used', 'data_consistency :delayed'
+  end
+
+  describe 'GraphQL `field` method' do
+    before do
+      allow(cop).to receive(:in_graphql_types?).and_return(true)
+    end
+
+    include_examples 'sets flag as used', 'field :runners, Types::Ci::RunnerType.connection_type, null: true, feature_flag: :foo', 'foo'
+    include_examples 'sets flag as used', 'field :runners, null: true, feature_flag: :foo', 'foo'
+    include_examples 'does not set any flags as used', 'field :solution'
+    include_examples 'does not set any flags as used', 'field :runners, Types::Ci::RunnerType.connection_type'
+    include_examples 'does not set any flags as used', 'field :runners, Types::Ci::RunnerType.connection_type, null: true, description: "hello world"'
+    include_examples 'does not set any flags as used', 'field :solution, type: GraphQL::STRING_TYPE, null: true, description: "URL to the vulnerabilitys details page."'
+  end
+
+  describe "tracking of usage data metrics known events happens at the beginning of inspection" do
+    let(:usage_data_counters_known_event_feature_flags) { ['an_event_feature_flag'] }
+
+    before do
+      allow(cop).to receive(:usage_data_counters_known_event_feature_flags).and_return(usage_data_counters_known_event_feature_flags)
+    end
+
+    include_examples 'sets flag as used', "FEATURE_FLAG = :foo", %w[foo an_event_feature_flag]
+  end
+end

spec/support/gitlab_experiment.rb

@@ -4,16 +4,6 @@
 require 'gitlab/experiment/rspec'
 require_relative 'stub_snowplow'
 
-# This is a temporary fix until we have a larger discussion around the
-# challenges raised in https://gitlab.com/gitlab-org/gitlab/-/issues/300104
-require Rails.root.join('app', 'experiments', 'application_experiment')
-class ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
-  def initialize(...)
-    super(...)
-    Feature.persist_used!(feature_flag_name)
-  end
-end
-
 RSpec.configure do |config|
   config.include StubSnowplow, :experiment
 

spec/support/helpers/stub_experiments.rb

@@ -11,7 +11,6 @@ module StubExperiments
     allow(Gitlab::Experimentation).to receive(:active?).and_call_original
 
     experiments.each do |experiment_key, enabled|
-      Feature.persist_used!("#{experiment_key}#{feature_flag_suffix}")
       allow(Gitlab::Experimentation).to receive(:active?).with(experiment_key) { enabled }
     end
   end
@@ -26,7 +25,6 @@ module StubExperiments
     allow(Gitlab::Experimentation).to receive(:in_experiment_group?).and_call_original
 
     experiments.each do |experiment_key, enabled|
-      Feature.persist_used!("#{experiment_key}#{feature_flag_suffix}")
       allow(Gitlab::Experimentation).to receive(:in_experiment_group?).with(experiment_key, anything) { enabled }
     end
   end

spec/support/helpers/stubbed_feature.rb

@@ -4,14 +4,6 @@
 module StubbedFeature
   extend ActiveSupport::Concern
 
-  prepended do
-    cattr_reader(:persist_used) do
-      # persist feature flags in CI
-      # nil: indicates that we do not want to persist used feature flags
-      Gitlab::Utils.to_boolean(ENV['CI']) ? {} : nil
-    end
-  end
-
   class_methods do
     # Turn stubbed feature flags on or off.
     def stub=(stub)
@@ -41,8 +33,6 @@ module StubbedFeature
       feature_flag = super
       return feature_flag unless stub?
 
-      persist_used!(args.first)
-
       # If feature flag is not persisted we mark the feature flag as enabled
       # We do `m.call` as we want to validate the execution of method arguments
       # and a feature flag state if it is not persisted
@@ -52,17 +42,5 @@ module StubbedFeature
 
       feature_flag
     end
-
-    # This method creates a temporary file in `tmp/feature_flags`
-    # if feature flag was touched during execution
-    def persist_used!(name)
-      return unless persist_used
-      return if persist_used[name]
-
-      persist_used[name] = true
-      FileUtils.touch(
-        Rails.root.join('tmp', 'feature_flags', name.to_s + ".used")
-      )
-    end
   end
 end