[feat]Implement FullCalendar#rooms_to_resources and add tests

spec/services/full_calendar_formatter_spec.rb

@@ -3,12 +3,24 @@
 require 'spec_helper'
 
 describe FullCalendarFormatter do
-  let!(:room0) { create(:room) }
   let!(:room1) { create(:room) }
+  let!(:room2) { create(:room) }
 
   describe 'JSON formatting for FullCalendar' do
     it 'translates rooms to resources' do
-      room_list = [room1, room2] # TODO
+      rooms = [room1, room2]
+      resources = described_class.rooms_to_resources(rooms)
+      expected_json = [
+        {
+          id:    room1.guid,
+          title: room1.name
+        },
+        {
+          id:    room2.guid,
+          title: room2.name
+        }
+      ].to_json
+      expect(resources).to eq(expected_json)
     end
   end
 end