Add wiki_events feature flag

This ensures that the methods we use for retrieving events respect the
:wiki_events feature flag.

This flag must be applied in two places - both in the event_collection
and in the events_finder, since there exist places in the code base
where the event_collection is used without the finder (for example in
the projects or the groups controllers) so it must be applied there, but
in the events_finder there is a branch that by-passes the
event_collection, so we also need it in the finder.

To support this flag, we have a new scope `Event.not_wiki_page`, which
only returns events that are not wiki page events.

This flag is off by default.

This includes improvements to the event collection spec by asserting
identity rather than length of results.

Includes suggested changes from reviewer (@.luke)

Co-authored-by: @.luke

app/finders/events_finder.rb

@@ -52,10 +52,17 @@ class EventsFinder
     if current_user && scope == 'all'
       EventCollection.new(current_user.authorized_projects).all_project_events
     else
-      source.events
+      # EventCollection is responsible for applying the feature flag
+      apply_feature_flags(source.events)
     end
   end
 
+  def apply_feature_flags(events)
+    return events if ::Feature.enabled?(:wiki_events)
+
+    events.not_wiki_page
+  end
+
   # rubocop: disable CodeReuse/ActiveRecord
   def by_current_user_access(events)
     events.merge(Project.public_or_visible_to_user(current_user))

app/models/event.rb

@@ -82,6 +82,7 @@ class Event < ApplicationRecord
   scope :code_push, -> { where(action: PUSHED) }
   scope :merged, -> { where(action: MERGED) }
   scope :for_wiki_page, -> { where(target_type: WikiPage::Meta.name) }
+  scope :not_wiki_page, -> { where('target_type IS NULL or target_type <> ?', WikiPage::Meta.name) }
 
   scope :with_associations, -> do
     # We're using preload for "push_event_payload" as otherwise the association

app/models/event_collection.rb

@@ -33,16 +33,23 @@ class EventCollection
                  project_events
                end
 
+    relation = apply_feature_flags(relation)
     relation = paginate_events(relation)
     relation.with_associations.to_a
   end
 
   def all_project_events
-    Event.from_union([project_events]).recent
+    apply_feature_flags(Event.from_union([project_events]).recent)
   end
 
   private
 
+  def apply_feature_flags(events)
+    return events if ::Feature.enabled?(:wiki_events)
+
+    events.not_wiki_page
+  end
+
   def project_events
     relation_with_join_lateral('project_id', projects)
   end

lib/event_filter.rb

@@ -23,6 +23,8 @@ class EventFilter
 
   # rubocop: disable CodeReuse/ActiveRecord
   def apply_filter(events)
+    events = apply_feature_flags(events)
+
     case filter
     when PUSH
       events.where(action: Event::PUSHED)
@@ -35,7 +37,7 @@ class EventFilter
     when ISSUE
       events.where(action: [Event::CREATED, Event::UPDATED, Event::CLOSED, Event::REOPENED], target_type: 'Issue')
     when WIKI
-      events.for_wiki_page
+      wiki_events(events)
     else
       events
     end
@@ -44,6 +46,18 @@ class EventFilter
 
   private
 
+  def apply_feature_flags(events)
+    return events.not_wiki_page unless Feature.enabled?(:wiki_events)
+
+    events
+  end
+
+  def wiki_events(events)
+    return events unless Feature.enabled?(:wiki_events)
+
+    events.for_wiki_page
+  end
+
   def filters
     [ALL, PUSH, MERGED, ISSUE, COMMENTS, TEAM, WIKI]
   end

spec/finders/events_finder_spec.rb

@@ -3,7 +3,7 @@
 require 'spec_helper'
 
 describe EventsFinder do
-  let(:user) { create(:user) }
+  let_it_be(:user) { create(:user) }
   let(:other_user) { create(:user) }
 
   let(:project1) { create(:project, :private, creator_id: user.id, namespace: user.namespace) }
@@ -20,7 +20,7 @@ describe EventsFinder do
   let(:opened_merge_request3) { create(:merge_request, source_project: project1, author: other_user) }
   let!(:other_developer_event) { create(:event, project: project1, author: other_user, target: opened_merge_request3, action: Event::CREATED) }
 
-  let(:public_project) { create(:project, :public, creator_id: user.id, namespace: user.namespace) }
+  let_it_be(:public_project) { create(:project, :public, creator_id: user.id, namespace: user.namespace) }
   let(:confidential_issue) { create(:closed_issue, confidential: true, project: public_project, author: user) }
   let!(:confidential_event) { create(:event, project: public_project, author: user, target: confidential_issue, action: Event::CLOSED) }
 
@@ -59,6 +59,32 @@ describe EventsFinder do
     end
   end
 
+  describe 'wiki events feature flag' do
+    let_it_be(:events) { create_list(:wiki_page_event, 3, project: public_project) }
+
+    subject(:finder) { described_class.new(source: public_project, target_type: 'wiki', current_user: user) }
+
+    context 'the wiki_events feature flag is disabled' do
+      before do
+        stub_feature_flags(wiki_events: false)
+      end
+
+      it 'omits the wiki page events' do
+        expect(finder.execute).to be_empty
+      end
+    end
+
+    context 'the wiki_events feature flag is enabled' do
+      before do
+        stub_feature_flags(wiki_events: true)
+      end
+
+      it 'can find the wiki events' do
+        expect(finder.execute).to match_array(events)
+      end
+    end
+  end
+
   context 'dashboard events' do
     before do
       project1.add_developer(other_user)

spec/lib/event_filter_spec.rb

@@ -79,6 +79,16 @@ describe EventFilter do
       it 'returns all events' do
         expect(filtered_events).to eq(Event.all)
       end
+
+      context 'the :wiki_events filter is disabled' do
+        before do
+          stub_feature_flags(wiki_events: false)
+        end
+
+        it 'does not return wiki events' do
+          expect(filtered_events).to eq(Event.not_wiki_page)
+        end
+      end
     end
 
     context 'with the "wiki" filter' do
@@ -87,6 +97,16 @@ describe EventFilter do
       it 'returns only wiki page events' do
         expect(filtered_events).to contain_exactly(wiki_page_event, wiki_page_update_event)
       end
+
+      context 'the :wiki_events filter is disabled' do
+        before do
+          stub_feature_flags(wiki_events: false)
+        end
+
+        it 'does not return wiki events' do
+          expect(filtered_events).not_to include(wiki_page_event, wiki_page_update_event)
+        end
+      end
     end
 
     context 'with an unknown filter' do
@@ -95,6 +115,16 @@ describe EventFilter do
       it 'returns all events' do
         expect(filtered_events).to eq(Event.all)
       end
+
+      context 'the :wiki_events filter is disabled' do
+        before do
+          stub_feature_flags(wiki_events: false)
+        end
+
+        it 'does not return wiki events' do
+          expect(filtered_events).to eq(Event.not_wiki_page)
+        end
+      end
     end
 
     context 'with a nil filter' do
@@ -103,6 +133,16 @@ describe EventFilter do
       it 'returns all events' do
         expect(filtered_events).to eq(Event.all)
       end
+
+      context 'the :wiki_events filter is disabled' do
+        before do
+          stub_feature_flags(wiki_events: false)
+        end
+
+        it 'does not return wiki events' do
+          expect(filtered_events).to eq(Event.not_wiki_page)
+        end
+      end
     end
   end
 

spec/models/event_collection_spec.rb

@@ -8,22 +8,68 @@ describe EventCollection do
     let_it_be(:project) { create(:project_empty_repo, group: group) }
     let_it_be(:projects) { Project.where(id: project.id) }
     let_it_be(:user) { create(:user) }
+    let_it_be(:merge_request) { create(:merge_request) }
 
     context 'with project events' do
-      before do
-        20.times do
-          event = create(:push_event, project: project, author: user)
-
-          create(:push_event_payload, event: event)
+      let_it_be(:push_event_payloads) do
+        Array.new(9) do
+          create(:push_event_payload,
+                 event: create(:push_event, project: project, author: user))
         end
-
-        create(:closed_issue_event, project: project, author: user)
       end
 
-      it 'returns an Array of events' do
+      let_it_be(:merge_request_events) { create_list(:event, 10, :commented, project: project, target: merge_request) }
+      let_it_be(:closed_issue_event) { create(:closed_issue_event, project: project, author: user) }
+      let_it_be(:wiki_page_event) { create(:wiki_page_event, project: project) }
+      let(:push_events) { push_event_payloads.map(&:event) }
+
+      it 'returns an Array of events', :aggregate_failures do
+        most_recent_20_events = [
+          wiki_page_event,
+          closed_issue_event,
+          *push_events,
+          *merge_request_events
+        ].sort_by(&:id).reverse.take(20)
         events = described_class.new(projects).to_a
 
         expect(events).to be_an_instance_of(Array)
+        expect(events).to match_array(most_recent_20_events)
+      end
+
+      context 'the wiki_events feature flag is disabled' do
+        before do
+          stub_feature_flags(wiki_events: false)
+        end
+
+        it 'omits the wiki page events when using to_a' do
+          events = described_class.new(projects).to_a
+
+          expect(events).not_to include(wiki_page_event)
+        end
+
+        it 'omits the wiki page events when using all_project_events' do
+          events = described_class.new(projects).all_project_events
+
+          expect(events).not_to include(wiki_page_event)
+        end
+      end
+
+      context 'the wiki_events feature flag is enabled' do
+        before do
+          stub_feature_flags(wiki_events: true)
+        end
+
+        it 'includes the wiki page events when using to_a' do
+          events = described_class.new(projects).to_a
+
+          expect(events).to include(wiki_page_event)
+        end
+
+        it 'includes the wiki page events when using all_project_events' do
+          events = described_class.new(projects).all_project_events
+
+          expect(events).to include(wiki_page_event)
+        end
       end
 
       it 'applies a limit to the number of events' do
@@ -44,12 +90,25 @@ describe EventCollection do
         expect(events).to be_empty
       end
 
-      it 'allows filtering of events using an EventFilter' do
+      it 'allows filtering of events using an EventFilter, returning single item' do
         filter = EventFilter.new(EventFilter::ISSUE)
         events = described_class.new(projects, filter: filter).to_a
 
-        expect(events.length).to eq(1)
-        expect(events[0].action).to eq(Event::CLOSED)
+        expect(events).to contain_exactly(closed_issue_event)
+      end
+
+      it 'allows filtering of events using an EventFilter, returning several items' do
+        filter = EventFilter.new(EventFilter::COMMENTS)
+        events = described_class.new(projects, filter: filter).to_a
+
+        expect(events).to match_array(merge_request_events)
+      end
+
+      it 'allows filtering of events using an EventFilter, returning pushes' do
+        filter = EventFilter.new(EventFilter::PUSH)
+        events = described_class.new(projects, filter: filter).to_a
+
+        expect(events).to match_array(push_events)
       end
     end
 

spec/models/event_spec.rb

@@ -454,9 +454,10 @@ describe Event do
     end
   end
 
-  describe '.for_wiki_page' do
+  describe 'wiki_page predicate scopes' do
     let_it_be(:events) do
       [
+        create(:push_event),
         create(:closed_issue_event),
         create(:wiki_page_event),
         create(:closed_issue_event),
@@ -465,10 +466,20 @@ describe Event do
       ]
     end
 
-    it 'only contains the wiki page events' do
-      wiki_events = events.select(&:wiki_page?)
+    describe '.for_wiki_page' do
+      it 'only contains the wiki page events' do
+        wiki_events = events.select(&:wiki_page?)
 
-      expect(described_class.for_wiki_page).to match_array(wiki_events)
+        expect(described_class.for_wiki_page).to match_array(wiki_events)
+      end
+    end
+
+    describe '.not_wiki_page' do
+      it 'does not contain the wiki page events' do
+        non_wiki_events = events.reject(&:wiki_page?)
+
+        expect(described_class.not_wiki_page).to match_array(non_wiki_events)
+      end
     end
   end