Does not remove board from project when project have only one board

app/services/boards/destroy_service.rb

 module Boards
   class DestroyService < Boards::BaseService
     def execute(board)
+      return false if project.boards.size == 1
+
       board.destroy
     end
   end

spec/controllers/projects/boards_controller_spec.rb

@@ -239,7 +239,8 @@ describe Projects::BoardsController do
   end
 
   describe 'DELETE destroy' do
-    let!(:board) { create(:board, project: project) }
+    let!(:boards) { create_pair(:board, project: project) }
+    let(:board)   { project.boards.first }
 
     context 'with valid board id' do
       it 'redirects to the issue boards page' do

spec/services/boards/destroy_service_spec.rb

@@ -2,13 +2,23 @@ require 'spec_helper'
 
 describe Boards::DestroyService, services: true do
   describe '#execute' do
-    it 'removes board from project' do
-      project = create(:empty_project)
-      board   = create(:board, project: project)
+    let(:project) { create(:empty_project) }
+    let!(:board)  { create(:board, project: project) }
 
-      service = described_class.new(project, double)
+    subject(:service) { described_class.new(project, double) }
 
-      expect { service.execute(board) }.to change(project.boards, :count).by(-1)
+    context 'when project have more than one board' do
+      it 'removes board from project' do
+        create(:board, project: project)
+
+        expect { service.execute(board) }.to change(project.boards, :count).by(-1)
+      end
+    end
+
+    context 'when project have one board' do
+      it 'does not remove board from project' do
+        expect { service.execute(board) }.not_to change(project.boards, :count)
+      end
     end
   end
 end