Filter out active periods

app/helpers/locations_helper.rb

@@ -51,9 +51,10 @@ module LocationsHelper
       active_periods.find {|x| x.to.nil?}.to = deactivation.deactivation_date
       active_periods << ActivePeriod.new(deactivation.reactivation_date, nil)
     end
-
+    
+    filtered_active_periods = active_periods.select {|period| period.to.nil? || (period.from.present? && period.from <= period.to)}
     availability = ""
-    active_periods.each do |period|
+    filtered_active_periods.each do |period|
       if period.from.present? 
       availability << "\nActive from #{period.from.to_formatted_s(:govuk_date)}"
       availability << " to #{(period.to - 1.day).to_formatted_s(:govuk_date)}\nDeactivated on #{period.to.to_formatted_s(:govuk_date)}" if period.to.present?

spec/helpers/locations_helper_spec.rb

@@ -154,6 +154,19 @@ RSpec.describe LocationsHelper do
           end
         end
       end
+
+      context "with intersecting deactivations" do
+        before do
+          location.location_deactivation_periods << FactoryBot.create(:location_deactivation_period, deactivation_date: Time.zone.local(2022, 10, 10), reactivation_date: Time.zone.local(2022, 12, 1))
+          location.location_deactivation_periods << FactoryBot.create(:location_deactivation_period, deactivation_date: Time.zone.local(2022, 11, 11), reactivation_date: Time.zone.local(2022, 12, 11))
+        end
+
+        it "displays the timeline of availability" do
+          availability_attribute = display_location_attributes(location).find { |x| x[:name] == "Availability" }[:value]
+
+          expect(availability_attribute).to eq("Active from 1 April 2022 to 9 October 2022\nDeactivated on 10 October 2022\nActive from 11 December 2022")
+        end
+      end
     end
   end
 end