Add feature flag

Without the feature flag, the DescendantCountService
functionality is used instead

app/graphql/gitlab_schema.rb

@@ -28,7 +28,7 @@ class GitlabSchema < GraphQL::Schema
 
   default_max_page_size 100
 
-  lazy_resolve Epics::LazyEpicAggregate, :epic_aggregate
+  lazy_resolve ::Epics::LazyEpicAggregate, :epic_aggregate
 
   class << self
     def multiplex(queries, **kwargs)

app/models/issue.rb

@@ -74,6 +74,8 @@ class Issue < ApplicationRecord
   scope :public_only, -> { where(confidential: false) }
   scope :confidential_only, -> { where(confidential: true) }
 
+  scope :counts_by_state, -> { reorder(nil).group(:state_id).count }
+
   ignore_column :state, remove_with: '12.7', remove_after: '2019-12-22'
 
   after_commit :expire_etag_cache, unless: :importing?

ee/app/models/ee/epic.rb

@@ -102,6 +102,8 @@ module EE
       scope :start_date_inherited, -> { where(start_date_is_fixed: [nil, false]) }
       scope :due_date_inherited, -> { where(due_date_is_fixed: [nil, false]) }
 
+      scope :counts_by_state, -> { group(:state_id).count }
+
       MAX_HIERARCHY_DEPTH = 5
 
       def etag_caching_enabled?

ee/spec/requests/api/graphql/group/epic/epic_aggregate_query_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe 'Epic aggregates (count and weight)' do
+describe 'Query epic aggregates (count and weight)' do
   include GraphqlHelpers
 
   let_it_be(:current_user) { create(:user) }
@@ -54,11 +54,6 @@ describe 'Epic aggregates (count and weight)' do
 
   it_behaves_like 'a working graphql query'
 
-  context 'with feature flag enabled' do
-    before do
-      stub_feature_flags(unfiltered_epic_aggregates: true)
-    end
-
   it 'returns the epic counts' do
     epic_count_result = {
       "openedEpics" => 1,
@@ -91,51 +86,4 @@ describe 'Epic aggregates (count and weight)' do
       a_hash_including('descendantWeightSum' => a_hash_including(descendant_weight_result))
     )
   end
-  end
-
-  context 'with feature flag disabled' do
-    before do
-      stub_feature_flags(unfiltered_epic_aggregates: false)
-    end
-
-    context 'when requesting counts' do
-      let(:epic_aggregates_query) do
-        <<~QUERY
-          nodes {
-            descendantCounts {
-              openedEpics
-              closedEpics
-              openedIssues
-              closedIssues
-            }
-          }
-        QUERY
-      end
-
-      it 'uses the DescendantCountService' do
-        expect(Epics::DescendantCountService).to receive(:new)
-
-        post_graphql(query, current_user: current_user)
-      end
-    end
-
-    context 'when requesting weights' do
-      let(:epic_aggregates_query) do
-        <<~QUERY
-          nodes {
-            descendantWeightSum {
-              openedIssues
-              closedIssues
-            }
-          }
-        QUERY
-      end
-
-      it 'returns an error' do
-        post_graphql(query, current_user: current_user)
-
-        expect_graphql_errors_to_include /Field 'descendantWeightSum' doesn't exist on type 'Epic/
-      end
-    end
-  end
 end