fix: Fix a small edge case with datetime computation (#1713)

app/services/utils/datetime_service.rb

@@ -12,6 +12,7 @@ def self.date_diff_with_timezone(from_datetime, to_datetime, timezone)
 
       to = to_datetime
       to = Time.zone.parse(to.to_s) unless to.is_a?(ActiveSupport::TimeWithZone)
+      to += 1.second if to == to.beginning_of_day # To make sure we do not miss a day
 
       from_offset = from.in_time_zone(timezone).utc_offset
       to_offset = to.in_time_zone(timezone).utc_offset

spec/scenarios/charge_models/prorated_graduated_spec.rb

@@ -403,7 +403,7 @@
             aggregate_failures do
               expect(subscription.reload).to be_terminated
               expect(subscription.reload.invoices.count).to eq(1)
-              expect(invoice.total_amount_cents).to eq(226)
+              expect(invoice.total_amount_cents).to eq(258)
               expect(invoice.issuing_date.iso8601).to eq('2023-12-07')
             end
           end
@@ -1050,7 +1050,7 @@
             aggregate_failures do
               expect(subscription.reload).to be_terminated
               expect(subscription.reload.invoices.count).to eq(1)
-              expect(invoice.total_amount_cents).to eq(4_145)
+              expect(invoice.total_amount_cents).to eq(4_161)
               expect(invoice.issuing_date.iso8601).to eq('2023-12-07')
             end
           end

spec/services/utils/datetime_service_spec.rb

@@ -59,6 +59,16 @@
         expect(result).to eq(31)
       end
     end
+
+    context 'with to date is the beginning of the day' do
+      let(:from_datetime) { Time.zone.parse('2023-12-01T00:00:00') }
+      let(:to_datetime) { Time.zone.parse('2023-12-07T00:00:00') }
+      let(:timezone) { 'UTC' }
+
+      it 'ensures it counts the full days' do
+        expect(result).to eq(7)
+      end
+    end
   end
 
   describe '.period_total_length_in_days' do