Add an endpoint to generate the default lists for a board

app/controllers/projects/board_lists_controller.rb

@@ -33,6 +33,16 @@ class Projects::BoardListsController < Projects::ApplicationController
     end
   end
+  def generate
+    service = Boards::Lists::GenerateService.new(project, current_user)
+
+    if service.execute
+      render json: project.board.lists.label.as_json(only: [:id, :list_type, :position], methods: [:title], include: { label: { only: [:id, :title, :color] } })
+    else
+      head :unprocessable_entity
+    end
+  end
+
   private
   def list_params

config/routes.rb

@@ -860,6 +860,10 @@ Rails.application.routes.draw do
           resources :issues, only: [:update], controller: :board_issues
           resources :lists, only: [:create, :update, :destroy], controller: :board_lists do
+            collection do
+              post :generate
+            end
+
             resources :issues, only: [:index], controller: :board_issues
           end
         end

spec/controllers/projects/board_lists_controller_spec.rb

@@ -119,4 +119,36 @@ describe Projects::BoardListsController do
                        format: :json
     end
   end
+
+  describe 'POST #generate' do
+    context 'when board lists is empty' do
+      it 'returns a successful 200 response' do
+        generate_default_board_lists
+
+        expect(response).to have_http_status(200)
+      end
+
+      it 'returns the defaults lists' do
+        generate_default_board_lists
+
+        expect(response).to match_response_schema('list', array: true)
+      end
+    end
+
+    context 'when board lists is not empty' do
+      it 'returns a unprocessable entity 422 response' do
+        create(:list, board: board)
+
+        generate_default_board_lists
+
+        expect(response).to have_http_status(422)
+      end
+    end
+
+    def generate_default_board_lists
+      post :generate, namespace_id: project.namespace.to_param,
+                      project_id: project.to_param,
+                      format: :json
+    end
+  end
 end