Allow to filter epics by timeframe or state using GraphQL

Add GraphQL parameters for epics to allow filtering by state, start_date
and end_date.

ee/app/finders/epics_finder.rb

@@ -92,8 +92,8 @@ class EpicsFinder < IssuableFinder
   def by_timeframe(items)
     return items unless params[:start_date] && params[:end_date]
 
-    end_date = params[:end_date].to_datetime.end_of_day
-    start_date = params[:start_date].to_datetime.beginning_of_day
+    end_date = params[:end_date].to_date
+    start_date = params[:start_date].to_date
 
     items
       .where('epics.start_date is not NULL or epics.end_date is not NULL')

ee/app/graphql/resolvers/epic_resolver.rb

@@ -10,12 +10,26 @@ module Resolvers
              required: false,
              description: 'The list of IIDs of epics, e.g., [1, 2]'
 
+    argument :state, Types::EpicStateEnum,
+             required: false,
+             description: 'Filter epics by state'
+
+    argument :start_date, Types::TimeType,
+             required: false,
+             description: 'List epics within a time frame where epics.start_date is between start_date and end_date parameters (end_date parameter must be present)'
+
+    argument :end_date, Types::TimeType,
+             required: false,
+             description: 'List epics within a time frame where epics.end_date is between start_date and end_date parameters (start_date parameter must be present)'
+
     type Types::EpicType, null: true
 
     def resolve(**args)
       return [] unless object.present?
       return [] unless epic_feature_enabled?
 
+      validate_date_params!(args)
+
       find_epics(transform_args(args))
     end
 
@@ -29,6 +43,16 @@ module Resolvers
       group.feature_available?(:epics)
     end
 
+    def validate_date_params!(args)
+      return unless args[:start_date].present? || args[:end_date].present?
+
+      date_params_complete = args[:start_date] && args[:end_date]
+
+      unless date_params_complete
+        raise Gitlab::Graphql::Errors::ArgumentError, "Both start_date and end_date must be present."
+      end
+    end
+
     def transform_args(args)
       transformed             = args.dup
       transformed[:group_id]  = group.id

ee/changelogs/unreleased/issue_12887.yml

+---
+title: Allow to filter epics by timeframe or state using GraphQL
+merge_request: 15110
+author:
+type: added

ee/spec/graphql/resolvers/epic_resolver_spec.rb

@@ -60,6 +60,48 @@ describe Resolvers::EpicResolver do
         end
       end
 
+      context 'within timeframe' do
+        let!(:epic1) { create(:epic, group: group, state: :closed, start_date: "2019-08-13", end_date: "2019-08-20") }
+        let!(:epic2) { create(:epic, group: group, state: :closed, start_date: "2019-08-13", end_date: "2019-08-21") }
+
+        context 'when start_date and end_date are present' do
+          it 'returns epics within timeframe' do
+            epics = resolve_epics(start_date: '2019-08-13', end_date: '2019-08-21')
+
+            expect(epics).to match_array([epic1, epic2])
+          end
+        end
+
+        context 'when only start_date is present' do
+          it 'returns epics within timeframe' do
+            expect { resolve_epics(start_date: '2019-08-13') }.to raise_error(Gitlab::Graphql::Errors::ArgumentError)
+          end
+        end
+
+        context 'when only end_date is present' do
+          it 'returns epics within timeframe' do
+            expect { resolve_epics(end_date: '2019-08-13') }.to raise_error(Gitlab::Graphql::Errors::ArgumentError)
+          end
+        end
+      end
+
+      context 'with state' do
+        let!(:epic1) { create(:epic, group: group, state: :opened, start_date: "2019-08-13", end_date: "2019-08-20") }
+        let!(:epic2) { create(:epic, group: group, state: :closed, start_date: "2019-08-13", end_date: "2019-08-21") }
+
+        it 'lists epics with opened state' do
+          epics = resolve_epics(state: 'opened')
+
+          expect(epics).to match_array([epic1])
+        end
+
+        it 'lists epics with closed state' do
+          epics = resolve_epics(state: 'closed')
+
+          expect(epics).to match_array([epic2])
+        end
+      end
+
       context 'with subgroups' do
         let(:sub_group) { create(:group, parent: group) }
         let(:iids)      { [epic1, epic2].map(&:iid) }