Improve `#stub_feature_flags` semantic

This changes the `#stub_feature_flags` to be:

- `stub_feature_flags(ci_live_trace: false)`
  Disable `ci_live_trace` feature flag globally

- `stub_feature_flags(ci_live_trace: project)`
- `stub_feature_flags(ci_live_trace: [project1, project2])`
  Enable `ci_live_trace` feature flag only on the specified projects

Which does represent an actual behaviour of `Flipper`:

1. You can enable selectively: enable means create override
   for a specific gate
2. You cannot disable selectively: disable means remove override
   for a specific gate

doc/development/testing_guide/best_practices.md

@@ -318,19 +318,41 @@ stub_feature_flags(ci_live_trace: false)
 Feature.enabled?(:ci_live_trace) # => false
 ```
 
-If you wish to set up a test where a feature flag is disabled for some
-actors and not others, you can specify this in options passed to the
-helper. For example, to disable the `ci_live_trace` feature flag for a
-specifc project:
+If you wish to set up a test where a feature flag is enabled only
+for some actors and not others, you can specify this in options
+passed to the helper. For example, to enable the `ci_live_trace`
+feature flag for a specifc project:
 
 ```ruby
 project1, project2 = build_list(:project, 2)
 
-# Feature will only be disabled for project1
-stub_feature_flags(ci_live_trace: { enabled: false, thing: project1 })
+# Feature will only be enabled for project1
+stub_feature_flags(ci_live_trace: project1)
 
-Feature.enabled?(:ci_live_trace, project1) # => false
-Feature.enabled?(:ci_live_trace, project2) # => true
+Feature.enabled?(:ci_live_trace) # => false
+Feature.enabled?(:ci_live_trace, project1) # => true
+Feature.enabled?(:ci_live_trace, project2) # => false
+```
+
+This represents an actual behavior of FlipperGate:
+
+1. You can enable an override for a specified actor to be enabled
+1. You can disable (remove) an override for a specified actor,
+   fallbacking to default state
+1. There's no way to model that you explicitly disable a specified actor
+
+```ruby
+Feature.enable(:my_feature)
+Feature.disable(:my_feature, project1)
+Feature.enabled?(:my_feature) # => true
+Feature.enabled?(:my_feature, project1) # => true
+```
+
+```ruby
+Feature.disable(:my_feature2)
+Feature.enable(:my_feature2, project1)
+Feature.enabled?(:my_feature2) # => false
+Feature.enabled?(:my_feature2, project1) # => true
 ```
 
 ### Pristine test environments

ee/spec/features/projects/navbar_spec.rb

@@ -97,7 +97,7 @@ describe 'Project navbar' do
   context 'when requirements is available' do
     before do
       stub_licensed_features(requirements: true)
-      stub_feature_flags(requirements_management: { enabled: true, thing: project })
+      stub_feature_flags(requirements_management: true)
 
       insert_after_nav_item(
         _('Merge Requests'),

ee/spec/features/projects/requirements_management/requirements_list_spec.rb

@@ -26,7 +26,7 @@ describe 'Requirements list', :js do
 
   before do
     stub_licensed_features(requirements: true)
-    stub_feature_flags(requirements_management: { enabled: true, thing: project })
+    stub_feature_flags(requirements_management: [project])
     project.add_maintainer(user)
     project.add_guest(user_guest)
 

ee/spec/helpers/ee/groups_helper_spec.rb

@@ -143,9 +143,7 @@ describe GroupsHelper do
 
   describe '#show_group_activity_analytics?' do
     before do
-      allow(Feature).to receive(:enabled?).with(:group_activity_analytics, group).and_return(false)
-      allow(Feature).to receive(:enabled?).with(:group_activity_analytics).and_return(true)
-
+      stub_feature_flags(group_activity_analytics: feature_available)
       stub_licensed_features(group_activity_analytics: feature_available)
 
       allow(helper).to receive(:current_user) { current_user }
@@ -238,9 +236,11 @@ describe GroupsHelper do
         expect(helper.show_administration_nav?(subgroup)).to be false
       end
 
-      context 'when `group_administration_nav_item` feature flag is disabled for the group' do
+      context 'when `group_administration_nav_item` feature flag is enabled for another group' do
+        let(:another_group) { create(:group) }
+
         before do
-          stub_feature_flags(group_administration_nav_item: { enabled: false, thing: group })
+          stub_feature_flags(group_administration_nav_item: another_group)
         end
 
         it 'returns false' do

ee/spec/lib/gitlab/auth/group_saml/sso_enforcer_spec.rb

@@ -45,7 +45,7 @@ describe Gitlab::Auth::GroupSaml::SsoEnforcer do
 
     describe 'enforced sso expiry' do
       before do
-        stub_feature_flags(enforced_sso_requires_session: { enabled: true, thing: saml_provider.group })
+        stub_feature_flags(enforced_sso_requires_session: saml_provider.group)
       end
 
       it 'returns true if a sign in is recently recorded' do
@@ -89,7 +89,7 @@ describe Gitlab::Auth::GroupSaml::SsoEnforcer do
     end
 
     it 'allows access when the sso enforcement feature is disabled' do
-      stub_feature_flags(enforced_sso: { enabled: false, thing: saml_provider.group })
+      stub_feature_flags(enforced_sso: false)
 
       expect(subject).not_to be_access_restricted
     end
@@ -110,7 +110,7 @@ describe Gitlab::Auth::GroupSaml::SsoEnforcer do
 
     context 'is restricted' do
       before do
-        stub_feature_flags(enforced_sso_requires_session: { enabled: true, thing: root_group })
+        stub_feature_flags(enforced_sso_requires_session: root_group)
       end
 
       it 'for a group' do
@@ -133,13 +133,13 @@ describe Gitlab::Auth::GroupSaml::SsoEnforcer do
     context 'is not restricted' do
       it 'for the group without configured saml_provider' do
         group = create(:group)
-        stub_feature_flags(enforced_sso_requires_session: { enabled: true, thing: group })
+        stub_feature_flags(enforced_sso_requires_session: group)
 
         expect(described_class).not_to be_group_access_restricted(group)
       end
 
       it 'for the group without the feature flag' do
-        stub_feature_flags(enforced_sso_requires_session: { enabled: false, thing: root_group })
+        stub_feature_flags(enforced_sso_requires_session: false)
 
         expect(described_class).not_to be_group_access_restricted(root_group)
       end

ee/spec/models/ci/build_spec.rb

@@ -83,7 +83,7 @@ describe Ci::Build do
 
     context 'and :ci_minutes_track_for_public_projects FF is disabled' do
       before do
-        stub_feature_flags(ci_minutes_track_for_public_projects: { enabled: false, thing: project.shared_runners_limit_namespace })
+        stub_feature_flags(ci_minutes_track_for_public_projects: false)
       end
 
       it_behaves_like 'depends on runner presence and type'

ee/spec/models/project_spec.rb

@@ -997,7 +997,7 @@ describe Project do
 
         context 'and :ci_minutes_track_for_public_projects FF is disabled' do
           before do
-            stub_feature_flags(ci_minutes_track_for_public_projects: { enabled: false, thing: project.shared_runners_limit_namespace })
+            stub_feature_flags(ci_minutes_track_for_public_projects: false)
           end
 
           it { is_expected.to be_falsey }

ee/spec/policies/group_policy_spec.rb

@@ -134,8 +134,7 @@ describe GroupPolicy do
     let(:current_user) { developer }
 
     before do
-      allow(Feature).to receive(:enabled?).with(:group_activity_analytics, group).and_return(false)
-
+      stub_feature_flags(group_activity_analytics: true)
       stub_licensed_features(group_activity_analytics: true)
     end
 
@@ -146,9 +145,7 @@ describe GroupPolicy do
     let(:current_user) { developer }
 
     before do
-      allow(Feature).to receive(:enabled?).with(:group_activity_analytics, group).and_return(false)
-      allow(Feature).to receive(:enabled?).with(:group_activity_analytics).and_return(true)
-
+      stub_feature_flags(group_activity_analytics: false)
       stub_licensed_features(group_activity_analytics: false)
     end
 

ee/spec/requests/api/analytics/group_activity_analytics_spec.rb

@@ -13,8 +13,7 @@ describe API::Analytics::GroupActivityAnalytics do
 
   shared_examples 'GET group_activity' do |activity, count|
     let(:feature_available) { true }
-    let(:feature_enabled_globally) { true }
-    let(:feature_enabled_for_group) { true }
+    let(:feature_enabled_for) { group }
     let(:params) { { group_path: group.full_path } }
     let(:current_user) { reporter }
     let(:request) do
@@ -22,25 +21,25 @@ describe API::Analytics::GroupActivityAnalytics do
     end
 
     before do
-      allow(Feature).to receive(:enabled?).with(:group_activity_analytics, group).and_return(feature_enabled_for_group)
-      allow(Feature).to receive(:enabled?).with(:group_activity_analytics).and_return(feature_enabled_globally)
-
+      stub_feature_flags(group_activity_analytics: feature_enabled_for)
       stub_licensed_features(group_activity_analytics: feature_available)
 
       request
     end
 
-    it 'is successful' do
-      expect(response).to have_gitlab_http_status(:ok)
-    end
+    context 'when feature is enabled for a group' do
+      it 'is successful' do
+        expect(response).to have_gitlab_http_status(:ok)
+      end
 
-    it 'is returns a count' do
-      expect(response.parsed_body).to eq({ "#{activity}_count" => count })
+      it 'is returns a count' do
+        expect(response.parsed_body).to eq({ "#{activity}_count" => count })
+      end
     end
 
     context 'when feature is not available in plan' do
       let(:feature_available) { false }
-      let(:feature_enabled_for_group) { false }
+      let(:feature_enabled_for) { false }
 
       it 'is returns `forbidden`' do
         expect(response).to have_gitlab_http_status(:forbidden)
@@ -48,8 +47,7 @@ describe API::Analytics::GroupActivityAnalytics do
     end
 
     context 'when feature is disabled globally' do
-      let(:feature_enabled_globally) { false }
-      let(:feature_enabled_for_group) { false }
+      let(:feature_enabled_for) { false }
 
       it 'is returns `forbidden`' do
         expect(response).to have_gitlab_http_status(:forbidden)

ee/spec/services/ee/merge_request_metrics_service_spec.rb

@@ -36,7 +36,7 @@ describe EE::MergeRequestMetricsService do
 
       context 'when `store_merge_request_line_metrics` feature flag is disabled' do
         before do
-          stub_feature_flags(store_merge_request_line_metrics: { enabled: false, thing: merge_request.target_project })
+          stub_feature_flags(store_merge_request_line_metrics: false)
         end
 
         it 'does not update line counts' do

ee/spec/support/shared_examples/features/insights_shared_examples.rb

@@ -80,7 +80,7 @@ RSpec.shared_examples 'Insights page' do
 
     context 'without correct license' do
       before do
-        stub_feature_flags(insights: { enabled: false, thing: entity })
+        stub_feature_flags(insights: false)
         stub_licensed_features(insights: false)
       end
 

ee/spec/support/shared_examples/models/alpha_beta_feature_support_shared_examples.rb

@@ -29,7 +29,7 @@ RSpec.shared_examples 'an entity with alpha/beta feature support' do
 
         context 'and enabled for the entity' do
           before do
-            stub_feature_flags(insights: { enabled: true, thing: entity })
+            stub_feature_flags(insights: entity)
           end
 
           it { expect(entity.public_send(method_name, :insights)).to be_truthy }
@@ -59,7 +59,7 @@ RSpec.shared_examples 'an entity with alpha/beta feature support' do
 
         context 'and enabled for the entity' do
           before do
-            stub_feature_flags(insights: { enabled: true, thing: entity })
+            stub_feature_flags(insights: entity)
           end
 
           it { expect(entity.public_send(method_name, :insights)).to be_truthy }

spec/controllers/groups/settings/integrations_controller_spec.rb

@@ -27,7 +27,7 @@ describe Groups::Settings::IntegrationsController do
 
       context 'when group_level_integrations not enabled' do
         it 'returns not_found' do
-          stub_feature_flags(group_level_integrations: { enabled: false, thing: group })
+          stub_feature_flags(group_level_integrations: false)
 
           get :index, params: { group_id: group }
 
@@ -60,7 +60,7 @@ describe Groups::Settings::IntegrationsController do
 
       context 'when group_level_integrations not enabled' do
         it 'returns not_found' do
-          stub_feature_flags(group_level_integrations: { enabled: false, thing: group })
+          stub_feature_flags(group_level_integrations: false)
 
           get :edit, params: { group_id: group, id: Service.available_services_names.sample }
 

spec/controllers/groups/settings/repository_controller_spec.rb

@@ -15,7 +15,7 @@ describe Groups::Settings::RepositoryController do
   describe 'POST create_deploy_token' do
     context 'when ajax_new_deploy_token feature flag is disabled for the project' do
       before do
-        stub_feature_flags(ajax_new_deploy_token: { enabled: false, thing: group })
+        stub_feature_flags(ajax_new_deploy_token: false)
         entity.add_owner(user)
       end
 

spec/controllers/projects/pipelines_controller_spec.rb

@@ -858,7 +858,7 @@ describe Projects::PipelinesController do
 
       context 'when junit_pipeline_screenshots_view is enabled' do
         before do
-          stub_feature_flags(junit_pipeline_screenshots_view: { enabled: true, thing: project })
+          stub_feature_flags(junit_pipeline_screenshots_view: project)
         end
 
         context 'when test_report contains attachment and scope is with_attachment as a URL param' do
@@ -887,7 +887,7 @@ describe Projects::PipelinesController do
 
       context 'when junit_pipeline_screenshots_view is disabled' do
         before do
-          stub_feature_flags(junit_pipeline_screenshots_view: { enabled: false, thing: project })
+          stub_feature_flags(junit_pipeline_screenshots_view: false)
         end
 
         context 'when test_report contains attachment and scope is with_attachment as a URL param' do

spec/controllers/projects/settings/repository_controller_spec.rb

@@ -36,7 +36,7 @@ describe Projects::Settings::RepositoryController do
   describe 'POST create_deploy_token' do
     context 'when ajax_new_deploy_token feature flag is disabled for the project' do
       before do
-        stub_feature_flags(ajax_new_deploy_token: { enabled: false, thing: project })
+        stub_feature_flags(ajax_new_deploy_token: false)
       end
 
       it_behaves_like 'a created deploy token' do

spec/features/explore/groups_spec.rb

@@ -27,7 +27,7 @@ describe 'Explore Groups', :js do
   end
 
   before do
-    stub_feature_flags({ vue_issuables_list: { enabled: false, thing: group } })
+    stub_feature_flags(vue_issuables_list: false)
   end
 
   shared_examples 'renders public and internal projects' do

spec/features/groups/issues_spec.rb

@@ -12,7 +12,7 @@ describe 'Group issues page' do
   let(:path) { issues_group_path(group) }
 
   before do
-    stub_feature_flags({ vue_issuables_list: { enabled: false, thing: group } })
+    stub_feature_flags(vue_issuables_list: false)
   end
 
   context 'with shared examples' do

spec/features/merge_request/maintainer_edits_fork_spec.rb

@@ -20,7 +20,7 @@ describe 'a maintainer edits files on a source-branch of an MR from a fork', :js
   end
 
   before do
-    stub_feature_flags(web_ide_default: false, single_mr_diff_view: { enabled: false, thing: target_project }, code_navigation: false)
+    stub_feature_flags(web_ide_default: false, single_mr_diff_view: false, code_navigation: false)
 
     target_project.add_maintainer(user)
     sign_in(user)

spec/features/merge_request/user_interacts_with_batched_mr_diffs_spec.rb

@@ -10,7 +10,7 @@ describe 'Batch diffs', :js do
   let(:merge_request) { create(:merge_request, source_project: project, source_branch: 'master', target_branch: 'empty-branch') }
 
   before do
-    stub_feature_flags(single_mr_diff_view: { enabled: true, thing: project })
+    stub_feature_flags(single_mr_diff_view: project)
     stub_feature_flags(diffs_batch_load: true)
 
     sign_in(project.owner)

spec/features/projects/settings/repository_settings_spec.rb

@@ -30,7 +30,7 @@ describe 'Projects > Settings > Repository settings' do
 
       before do
         stub_container_registry_config(enabled: true)
-        stub_feature_flags(ajax_new_deploy_token: { enabled: false, thing: project })
+        stub_feature_flags(ajax_new_deploy_token: project)
         visit project_settings_repository_path(project)
       end
 
@@ -225,7 +225,7 @@ describe 'Projects > Settings > Repository settings' do
     # Removal: https://gitlab.com/gitlab-org/gitlab/-/issues/208828
     context 'with the `keep_divergent_refs` feature flag disabled' do
       before do
-        stub_feature_flags(keep_divergent_refs: { enabled: false, thing: project })
+        stub_feature_flags(keep_divergent_refs: false)
       end
 
       it 'hides the "Keep divergent refs" option' do

spec/features/projects/settings/user_sees_revoke_deploy_token_modal_spec.rb

@@ -11,7 +11,7 @@ describe 'Repository Settings > User sees revoke deploy token modal', :js do
   before do
     project.add_role(user, role)
     sign_in(user)
-    stub_feature_flags(ajax_new_deploy_token: { enabled: false, thing: project })
+    stub_feature_flags(ajax_new_deploy_token: project)
     visit(project_settings_repository_path(project))
     click_link('Revoke')
   end

spec/finders/fork_projects_finder_spec.rb

@@ -14,7 +14,7 @@ describe ForkProjectsFinder do
   let(:private_fork_member) { create(:user) }
 
   before do
-    stub_feature_flags(object_pools: { enabled: false, thing: source_project })
+    stub_feature_flags(object_pools: source_project)
 
     private_fork.update!(visibility_level: Gitlab::VisibilityLevel::PRIVATE)
     private_fork.add_developer(private_fork_member)

spec/lib/gitlab/import_export/relation_tree_restorer_spec.rb

@@ -64,7 +64,7 @@ describe Gitlab::ImportExport::RelationTreeRestorer do
   shared_examples 'logging of relations creation' do
     context 'when log_import_export_relation_creation feature flag is enabled' do
       before do
-        stub_feature_flags(log_import_export_relation_creation: { enabled: true, thing: group })
+        stub_feature_flags(log_import_export_relation_creation: group)
       end
 
       it 'logs top-level relation creation' do
@@ -79,7 +79,7 @@ describe Gitlab::ImportExport::RelationTreeRestorer do
 
     context 'when log_import_export_relation_creation feature flag is disabled' do
       before do
-        stub_feature_flags(log_import_export_relation_creation: { enabled: false, thing: group })
+        stub_feature_flags(log_import_export_relation_creation: false)
       end
 
       it 'does not log top-level relation creation' do

spec/lib/gitlab/tracking_spec.rb

@@ -28,17 +28,13 @@ describe Gitlab::Tracking do
     end
 
     it 'enables features using feature flags' do
-      stub_feature_flags(additional_snowplow_tracking: true)
-      allow(Feature).to receive(:enabled?).with(
-        :additional_snowplow_tracking,
-        '_group_'
-      ).and_return(false)
+      stub_feature_flags(additional_snowplow_tracking: :__group__)
       addition_feature_fields = {
         formTracking: false,
         linkClickTracking: false
       }
 
-      expect(subject.snowplow_options('_group_')).to include(addition_feature_fields)
+      expect(subject.snowplow_options(:_group_)).to include(addition_feature_fields)
     end
   end
 

spec/lib/gitlab/wiki_pages/front_matter_parser_spec.rb

@@ -76,11 +76,7 @@ describe Gitlab::WikiPages::FrontMatterParser do
       let(:raw_content) { with_front_matter }
 
       before do
-        stub_feature_flags(Gitlab::WikiPages::FrontMatterParser::FEATURE_FLAG => false)
-        stub_feature_flags(Gitlab::WikiPages::FrontMatterParser::FEATURE_FLAG => {
-          enabled: true,
-          thing: gate
-        })
+        stub_feature_flags(Gitlab::WikiPages::FrontMatterParser::FEATURE_FLAG => gate)
       end
 
       it do

spec/models/wiki_page_spec.rb

@@ -16,10 +16,7 @@ describe WikiPage do
   end
 
   def enable_front_matter_for(thing)
-    stub_feature_flags(Gitlab::WikiPages::FrontMatterParser::FEATURE_FLAG => {
-      thing: thing,
-      enabled: true
-    })
+    stub_feature_flags(Gitlab::WikiPages::FrontMatterParser::FEATURE_FLAG => thing)
   end
 
   describe '.group_by_directory' do

spec/requests/api/internal/base_spec.rb

@@ -452,7 +452,7 @@ describe API::Internal::Base do
 
           context 'when gitaly_upload_pack_filter feature flag is disabled' do
             before do
-              stub_feature_flags(gitaly_upload_pack_filter: { enabled: false, thing: project })
+              stub_feature_flags(gitaly_upload_pack_filter: false)
             end
 
             it 'returns only maxInputSize and not partial clone git config' do
@@ -481,7 +481,7 @@ describe API::Internal::Base do
 
           context 'when gitaly_upload_pack_filter feature flag is disabled' do
             before do
-              stub_feature_flags(gitaly_upload_pack_filter: { enabled: false, thing: project })
+              stub_feature_flags(gitaly_upload_pack_filter: false)
             end
 
             it 'returns an empty git config' do

spec/requests/api/remote_mirrors_spec.rb

@@ -107,7 +107,7 @@ describe API::RemoteMirrors do
 
     context 'with the `keep_divergent_refs` feature enabled' do
       before do
-        stub_feature_flags(keep_divergent_refs: { enabled: true, project: project })
+        stub_feature_flags(keep_divergent_refs: project)
       end
 
       it 'updates the `keep_divergent_refs` attribute' do

spec/requests/api/search_spec.rb

@@ -163,7 +163,7 @@ describe API::Search do
 
         context 'when users search feature is disabled' do
           before do
-            allow(Feature).to receive(:disabled?).with(:users_search, default_enabled: true).and_return(true)
+            stub_feature_flags(users_search: false)
 
             get api(endpoint, user), params: { scope: 'users', search: 'billy' }
           end
@@ -336,7 +336,7 @@ describe API::Search do
 
         context 'when users search feature is disabled' do
           before do
-            allow(Feature).to receive(:disabled?).with(:users_search, default_enabled: true).and_return(true)
+            stub_feature_flags(users_search: false)
 
             get api(endpoint, user), params: { scope: 'users', search: 'billy' }
           end
@@ -501,7 +501,7 @@ describe API::Search do
 
         context 'when users search feature is disabled' do
           before do
-            allow(Feature).to receive(:disabled?).with(:users_search, default_enabled: true).and_return(true)
+            stub_feature_flags(users_search: false)
 
             get api(endpoint, user), params: { scope: 'users', search: 'billy' }
           end

spec/services/git/wiki_push_service_spec.rb

@@ -264,7 +264,7 @@ describe Git::WikiPushService, services: true do
 
         context 'but is enabled for a given project' do
           before do
-            stub_feature_flags(wiki_events_on_git_push: { enabled: true, thing: project })
+            stub_feature_flags(wiki_events_on_git_push: project)
           end
 
           it 'creates events' do

spec/services/namespaces/check_storage_size_service_spec.rb

@@ -30,21 +30,14 @@ describe Namespaces::CheckStorageSizeService, '#execute' do
       expect(subject).to be_error
     end
 
-    it 'is successful when disabled for the current group' do
-      stub_feature_flags(namespace_storage_limit: { enabled: false, thing: root_group })
-
-      expect(subject).to be_success
-    end
-
     it 'is successful when feature flag is activated for another group' do
-      stub_feature_flags(namespace_storage_limit: false)
-      stub_feature_flags(namespace_storage_limit: { enabled: true, thing: create(:group) })
+      stub_feature_flags(namespace_storage_limit: create(:group))
 
       expect(subject).to be_success
     end
 
     it 'errors when feature flag is activated for the current group' do
-      stub_feature_flags(namespace_storage_limit: { enabled: true, thing: root_group })
+      stub_feature_flags(namespace_storage_limit: root_group)
 
       expect(subject).to be_error
     end

spec/spec_helper.rb

@@ -173,21 +173,19 @@ RSpec.configure do |config|
     # Enable all features by default for testing
     allow(Feature).to receive(:enabled?) { true }
 
-    enabled = example.metadata[:enable_rugged].present?
+    enable_rugged = example.metadata[:enable_rugged].present?
 
     # Disable Rugged features by default
     Gitlab::Git::RuggedImpl::Repository::FEATURE_FLAGS.each do |flag|
-      allow(Feature).to receive(:enabled?).with(flag).and_return(enabled)
+      stub_feature_flags(flag => enable_rugged)
     end
 
-    allow(Gitlab::GitalyClient).to receive(:can_use_disk?).and_return(enabled)
+    allow(Gitlab::GitalyClient).to receive(:can_use_disk?).and_return(enable_rugged)
 
     # The following can be removed when we remove the staged rollout strategy
     # and we can just enable it using instance wide settings
     # (ie. ApplicationSetting#auto_devops_enabled)
-    allow(Feature).to receive(:enabled?)
-      .with(:force_autodevops_on_by_default, anything)
-      .and_return(false)
+    stub_feature_flags(force_autodevops_on_by_default: false)
 
     # Enable Marginalia feature for all specs in the test suite.
     allow(Gitlab::Marginalia).to receive(:cached_feature_enabled?).and_return(true)
@@ -196,12 +194,8 @@ RSpec.configure do |config|
     # is feature-complete and can be made default in place
     # of older sidebar.
     # See https://gitlab.com/groups/gitlab-org/-/epics/1863
-    allow(Feature).to receive(:enabled?)
-      .with(:vue_issuable_sidebar, anything)
-      .and_return(false)
-    allow(Feature).to receive(:enabled?)
-      .with(:vue_issuable_epic_sidebar, anything)
-      .and_return(false)
+    stub_feature_flags(vue_issuable_sidebar: false)
+    stub_feature_flags(vue_issuable_epic_sidebar: false)
 
     # Stub these calls due to being expensive operations
     # It can be reenabled for specific tests via:

spec/support/helpers/stub_feature_flags.rb

@@ -9,23 +9,27 @@ module StubFeatureFlags
   # Examples
   # - `stub_feature_flags(ci_live_trace: false)` ... Disable `ci_live_trace`
   #   feature flag globally.
-  # - `stub_feature_flags(ci_live_trace: { enabled: false, thing: project })` ...
-  #   Disable `ci_live_trace` feature flag on the specified project.
+  # - `stub_feature_flags(ci_live_trace: project)` ...
+  # - `stub_feature_flags(ci_live_trace: [project1, project2])` ...
+  #   Enable `ci_live_trace` feature flag only on the specified projects.
   def stub_feature_flags(features)
-    features.each do |feature_name, option|
-      if option.is_a?(Hash)
-        enabled, thing = option.values_at(:enabled, :thing)
-      else
-        enabled = option
-        thing = nil
-      end
+    features.each do |feature_name, actors|
+      allow(Feature).to receive(:enabled?).with(feature_name, any_args).and_return(false)
+      allow(Feature).to receive(:enabled?).with(feature_name.to_s, any_args).and_return(false)
+
+      Array(actors).each do |actor|
+        raise ArgumentError, "actor cannot be Hash" if actor.is_a?(Hash)
 
-      if thing
-        allow(Feature).to receive(:enabled?).with(feature_name, thing, any_args) { enabled }
-        allow(Feature).to receive(:enabled?).with(feature_name.to_s, thing, any_args) { enabled }
-      else
-        allow(Feature).to receive(:enabled?).with(feature_name, any_args) { enabled }
-        allow(Feature).to receive(:enabled?).with(feature_name.to_s, any_args) { enabled }
+        case actor
+        when false, true
+          allow(Feature).to receive(:enabled?).with(feature_name, any_args).and_return(actor)
+          allow(Feature).to receive(:enabled?).with(feature_name.to_s, any_args).and_return(actor)
+        when nil, ActiveRecord::Base, Symbol, RSpec::Mocks::Double
+          allow(Feature).to receive(:enabled?).with(feature_name, actor, any_args).and_return(true)
+          allow(Feature).to receive(:enabled?).with(feature_name.to_s, actor, any_args).and_return(true)
+        else
+          raise ArgumentError, "#stub_feature_flags accepts only `nil`, `true`, `false`, `ActiveRecord::Base` or `Symbol` as actors"
+        end
       end
     end
   end

spec/support/shared_examples/serializers/diff_file_entity_shared_examples.rb

@@ -60,7 +60,7 @@ RSpec.shared_examples 'diff file entity' do
 
     context 'when the `single_mr_diff_view` feature is disabled' do
       before do
-        stub_feature_flags(single_mr_diff_view: { enabled: false, thing: project })
+        stub_feature_flags(single_mr_diff_view: false)
       end
 
       it 'contains both kinds of diffs' do

spec/support_specs/helpers/stub_feature_flags_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe StubFeatureFlags do
+  before do
+    # reset stub introduced by `stub_feature_flags`
+    allow(Feature).to receive(:enabled?).and_call_original
+  end
+
+  context 'if not stubbed' do
+    it 'features are disabled by default' do
+      expect(Feature.enabled?(:test_feature)).to eq(false)
+    end
+  end
+
+  describe '#stub_feature_flags' do
+    using RSpec::Parameterized::TableSyntax
+
+    let(:feature_name) { :test_feature }
+
+    context 'when checking global state' do
+      where(:feature_actors, :expected_result) do
+        false   | false
+        true    | true
+        :A      | false
+        %i[A]   | false
+        %i[A B] | false
+      end
+
+      with_them do
+        before do
+          stub_feature_flags(feature_name => feature_actors)
+        end
+
+        it { expect(Feature.enabled?(feature_name)).to eq(expected_result) }
+        it { expect(Feature.disabled?(feature_name)).not_to eq(expected_result) }
+
+        context 'default_enabled does not impact feature state' do
+          it { expect(Feature.enabled?(feature_name, default_enabled: true)).to eq(expected_result) }
+          it { expect(Feature.disabled?(feature_name, default_enabled: true)).not_to eq(expected_result) }
+        end
+      end
+    end
+
+    context 'when checking scoped state' do
+      where(:feature_actors, :tested_actor, :expected_result) do
+        false   | nil  | false
+        true    | nil  | true
+        false   | :A   | false
+        true    | :A   | true
+        :A      | nil  | false
+        :A      | :A   | true
+        :A      | :B   | false
+        %i[A]   | nil  | false
+        %i[A]   | :A   | true
+        %i[A]   | :B   | false
+        %i[A B] | nil  | false
+        %i[A B] | :A   | true
+        %i[A B] | :B   | true
+      end
+
+      with_them do
+        before do
+          stub_feature_flags(feature_name => feature_actors)
+        end
+
+        it { expect(Feature.enabled?(feature_name, tested_actor)).to eq(expected_result) }
+        it { expect(Feature.disabled?(feature_name, tested_actor)).not_to eq(expected_result) }
+
+        context 'default_enabled does not impact feature state' do
+          it { expect(Feature.enabled?(feature_name, tested_actor, default_enabled: true)).to eq(expected_result) }
+          it { expect(Feature.disabled?(feature_name, tested_actor, default_enabled: true)).not_to eq(expected_result) }
+        end
+      end
+    end
+
+    context 'type handling' do
+      context 'raises error' do
+        where(:feature_actors) do
+          ['string', 1, 1.0, OpenStruct.new]
+        end
+
+        with_them do
+          subject { stub_feature_flags(feature_name => feature_actors) }
+
+          it { expect { subject }.to raise_error(ArgumentError, /accepts only/) }
+        end
+      end
+
+      context 'does not raise error' do
+        where(:feature_actors) do
+          [true, false, nil, :symbol, double, User.new]
+        end
+
+        with_them do
+          subject { stub_feature_flags(feature_name => feature_actors) }
+
+          it { expect { subject }.not_to raise_error }
+        end
+      end
+    end
+
+    it 'subsquent run changes state' do
+      # enable FF only on A
+      stub_feature_flags(test_feature: %i[A])
+      expect(Feature.enabled?(:test_feature)).to eq(false)
+      expect(Feature.enabled?(:test_feature, :A)).to eq(true)
+      expect(Feature.enabled?(:test_feature, :B)).to eq(false)
+
+      # enable FF only on B
+      stub_feature_flags(test_feature: %i[B])
+      expect(Feature.enabled?(:test_feature)).to eq(false)
+      expect(Feature.enabled?(:test_feature, :A)).to eq(false)
+      expect(Feature.enabled?(:test_feature, :B)).to eq(true)
+
+      # enable FF on all
+      stub_feature_flags(test_feature: true)
+      expect(Feature.enabled?(:test_feature)).to eq(true)
+      expect(Feature.enabled?(:test_feature, :A)).to eq(true)
+      expect(Feature.enabled?(:test_feature, :B)).to eq(true)
+
+      # disable FF on all
+      stub_feature_flags(test_feature: false)
+      expect(Feature.enabled?(:test_feature)).to eq(false)
+      expect(Feature.enabled?(:test_feature, :A)).to eq(false)
+      expect(Feature.enabled?(:test_feature, :B)).to eq(false)
+    end
+  end
+end