Allow to create epic from ancestor board

When an epic is created from an epic board, user can
can select a group where the epic will be created. This group
can be either the same group as board's group or any subgroup.

For this reason when we are searching for the board, it can exist in
any ancestor group.

Changelog: added
EE: true

ee/app/finders/boards/epic_boards_finder.rb

@@ -10,7 +10,7 @@ module Boards
     end
 
     def execute
-      relation = group.epic_boards
+      relation = init_relation
       relation = by_id(relation)
 
       relation.order_by_name_asc
@@ -18,6 +18,12 @@ module Boards
 
     private
 
+    def init_relation
+      return group.epic_boards unless params[:include_ancestor_groups]
+
+      ::Boards::EpicBoard.for_groups(group.self_and_ancestors)
+    end
+
     def by_id(relation)
       return relation unless params[:id].present?
 

ee/app/models/boards/epic_board.rb

@@ -12,6 +12,7 @@ module Boards
     validates :name, length: { maximum: 255 }, presence: true
 
     scope :order_by_name_asc, -> { order(arel_table[:name].lower.asc).order(id: :asc) }
+    scope :for_groups, ->(ids) { where(group_id: ids) }
 
     def lists
       epic_lists

ee/app/services/boards/epics/create_service.rb

@@ -34,7 +34,10 @@ module Boards
       end
 
       def board
-        @board ||= parent.epic_boards.find(params.delete(:board_id))
+        @board ||= Boards::EpicBoardsFinder
+          .new(group, include_ancestor_groups: true, id: params.delete(:board_id))
+          .execute
+          .first
       end
 
       def list
@@ -50,10 +53,8 @@ module Boards
       end
 
       def check_arguments
-        begin
-          board
-        rescue ActiveRecord::RecordNotFound
-          return 'Board not found' if @board.blank?
+        unless board && Ability.allowed?(current_user, :read_epic_board, board)
+          return 'Board not found'
         end
 
         begin

ee/spec/finders/boards/epic_boards_finder_spec.rb

@@ -4,11 +4,13 @@ require 'spec_helper'
 
 RSpec.describe Boards::EpicBoardsFinder do
   describe '#execute' do
-    let_it_be(:group) { create(:group) }
+    let_it_be(:parent_group) { create(:group) }
+    let_it_be(:group) { create(:group, parent: parent_group) }
     let_it_be(:epic_board1) { create(:epic_board, name: 'Acd', group: group) }
     let_it_be(:epic_board2) { create(:epic_board, name: 'abd', group: group) }
     let_it_be(:epic_board3) { create(:epic_board, name: 'Bbd', group: group) }
     let_it_be(:epic_board4) { create(:epic_board) }
+    let_it_be(:epic_board5) { create(:epic_board, name: 'foo', group: parent_group) }
 
     let(:params) { {} }
 
@@ -18,6 +20,14 @@ RSpec.describe Boards::EpicBoardsFinder do
       expect(result).to eq([epic_board2, epic_board1, epic_board3])
     end
 
+    context 'when include_ancestor_groups parameter is set' do
+      let(:params) { { include_ancestor_groups: true } }
+
+      it 'finds all epic boards in the group or ancestor groups' do
+        expect(result).to eq([epic_board2, epic_board1, epic_board3, epic_board5])
+      end
+    end
+
     context 'when ID parameter is set' do
       let(:params) { { id: epic_board2.id } }
 

ee/spec/models/boards/epic_board_spec.rb

@@ -15,13 +15,21 @@ RSpec.describe Boards::EpicBoard do
     it { is_expected.to validate_length_of(:name).is_at_most(255) }
   end
 
-  describe '.order_by_name_asc' do
+  describe 'scopes' do
     let_it_be(:board1) { create(:epic_board, name: 'B') }
     let_it_be(:board2) { create(:epic_board, name: 'a') }
     let_it_be(:board3) { create(:epic_board, name: 'A') }
 
-    it 'returns in case-insensitive alphabetical order and then by ascending ID' do
-      expect(described_class.order_by_name_asc).to eq [board2, board3, board1]
+    describe '.order_by_name_asc' do
+      it 'returns in case-insensitive alphabetical order and then by ascending ID' do
+        expect(described_class.order_by_name_asc).to eq [board2, board3, board1]
+      end
+    end
+
+    describe '.for_groups' do
+      it 'returns boards only in selected groups' do
+        expect(described_class.for_groups([board1.group_id, board2.group_id])).to match_array([board1, board2])
+      end
     end
   end
 end

ee/spec/services/boards/epics/create_service_spec.rb

@@ -4,7 +4,8 @@ require 'spec_helper'
 
 RSpec.describe Boards::Epics::CreateService do
   let_it_be(:user) { create(:user) }
-  let_it_be(:group) { create(:group) }
+  let_it_be(:parent_group) { create(:group) }
+  let_it_be(:group) { create(:group, parent: parent_group) }
   let_it_be(:board) { create(:epic_board, group: group) }
 
   describe '#execute' do
@@ -19,34 +20,41 @@ RSpec.describe Boards::Epics::CreateService do
 
     let(:params) { valid_params }
 
-    subject do
+    subject(:response) do
       described_class.new(group, user, params).execute
     end
 
     shared_examples 'epic creation error' do |error_pattern|
       it 'does not create epic' do
-        response = subject
-
         expect(response).to be_error
         expect(response.message).to match(error_pattern)
       end
     end
 
+    shared_examples 'success epic creation' do
+      it 'creates an epic' do
+        expect(response).to be_success
+        expect(response.payload).to be_a(Epic)
+      end
+
+      specify { expect { subject }.to change { Epic.count }.by(1) }
+    end
+
     context 'when epics feature is available' do
       before do
         stub_licensed_features(epics: true)
         group.add_developer(user)
       end
 
-      context 'when arguments are valid' do
-        it 'creates an epic' do
-          response = subject
+      it_behaves_like 'success epic creation'
 
-          expect(response).to be_success
-          expect(response.payload).to be_a(Epic)
-        end
+      context 'when board is in an ancestor group' do
+        let_it_be(:parent_board) { create(:epic_board, group: parent_group) }
+        let_it_be(:parent_list) { create(:epic_list, epic_board: parent_board) }
+
+        let(:params) { valid_params.merge(board_id: parent_board.id, list_id: parent_list.id) }
 
-        specify { expect { subject }.to change { Epic.count }.by(1) }
+        it_behaves_like 'success epic creation'
       end
 
       context 'when arguments are not valid' do