fix(subscription): Fix generating invoice with pending downgrade

app/services/subscriptions/dates_service.rb

@@ -64,13 +64,13 @@ def to_datetime
       return @to_datetime if @to_datetime
 
       @to_datetime = customer_timezone_shift(compute_to_date, end_of_day: true)
-      terminated_at = subscription.terminated_at&.change(usec: 0)
-      bill_at = billing_at&.change(usec: 0)
+      terminated_at = subscription.terminated_at&.to_time&.round
 
-      if subscription.terminated? && @to_datetime > terminated_at && bill_at && bill_at >= terminated_at
+      if subscription.terminated_at?(billing_at) && @to_datetime > terminated_at
         @to_datetime = terminated_at
       end
 
+      @to_datetime = subscription.started_at if @to_datetime < subscription.started_at
       @to_datetime
     end
 
@@ -96,6 +96,7 @@ def charges_from_datetime
     def charges_to_datetime
       datetime = customer_timezone_shift(compute_charges_to_date, end_of_day: true)
       datetime = subscription.terminated_at if subscription.terminated_at?(datetime)
+      datetime = subscription.started_at if datetime < subscription.started_at
 
       datetime
     end
@@ -151,6 +152,8 @@ def subscription_at
       subscription.subscription_at.in_time_zone(customer.applicable_timezone)
     end
 
+    # NOTE: This method converts a DAY epress in the customer timezone into a proper UTC datetime
+    #       Example: `2024-03-01` in `America/New_York` will be converted to `2024-03-01T05:00:00 UTC`
     def customer_timezone_shift(date, end_of_day: false)
       result = date.in_time_zone(customer.applicable_timezone)
       result = result.end_of_day if end_of_day

spec/models/invoice_spec.rb

@@ -633,9 +633,9 @@
   end
 
   describe '#charge_pay_in_advance_proration_range' do
-    let(:invoice_subscription) { create(:invoice_subscription) }
+    let(:invoice_subscription) { create(:invoice_subscription, subscription:) }
     let(:invoice) { invoice_subscription.invoice }
-    let(:subscription) { invoice_subscription.subscription }
+    let(:subscription) { create(:subscription, started_at: timestamp - 1.year) }
     let(:timestamp) { DateTime.parse('2023-07-25 00:00:00 UTC') }
     let(:event) { create(:event, subscription_id: subscription.id, timestamp:) }
     let(:billable_metric) { create(:sum_billable_metric, organization: subscription.organization, recurring: true) }

spec/scenarios/subscriptions/terminate_ended_spec.rb

@@ -18,9 +18,9 @@
     )
   end
 
-  let(:creation_time) { DateTime.new(2023, 9, 5, 0, 0) }
-  let(:subscription_at) { DateTime.new(2023, 9, 5, 0, 0) }
-  let(:ending_at) { DateTime.new(2023, 9, 6, 0, 0) }
+  let(:creation_time) { Time.zone.parse('2023-09-05T00:00:00') }
+  let(:subscription_at) { Time.zone.parse('2023-09-05T00:00:00') }
+  let(:ending_at) { Time.zone.parse('2023-09-06T00:00:00') }
 
   context 'when timezone is Europe/Paris' do
     it 'terminates the subscription when it reaches its ending date' do

spec/services/subscriptions/dates/monthly_service_spec.rb

@@ -205,23 +205,44 @@
 
       context 'when subscription is just terminated' do
         let(:billing_at) { Time.zone.parse('10 Mar 2022') }
+        let(:terminated_at) { Time.zone.parse('09 Mar 2022') }
 
-        before do
-          subscription.update!(
-            status: :terminated,
-            terminated_at: Time.zone.parse('02 Mar 2022')
-          )
-        end
+        before { subscription.update!(status: :terminated, terminated_at:) }
 
         it 'returns the termination date' do
-          expect(result).to eq(subscription.terminated_at.utc.to_s)
+          expect(result).to match_datetime(subscription.terminated_at.utc)
+        end
+
+        context 'with pending next subscription' do
+          let(:subscription_at) { Time.zone.parse('2024-09-09T14:00:01') }
+          let(:terminated_at) { Time.zone.parse('2024-09-09T16:00:01') }
+
+          let(:downgraded_plan) { create(:plan, interval: :monthly, pay_in_advance: false, amount_cents: 0) }
+
+          before do
+            create(
+              :subscription,
+              status: :pending,
+              external_id: subscription.external_id,
+              plan: downgraded_plan,
+              customer:,
+              subscription_at:,
+              billing_time:,
+              started_at: nil,
+              previous_subscription: subscription
+            )
+          end
+
+          it 'makes sure the to_datetime is not before start date' do
+            expect(result).to match_datetime(subscription.started_at.utc)
+          end
         end
 
         context 'with customer timezone' do
           let(:timezone) { 'America/New_York' }
 
           it 'returns the termination date' do
-            expect(result).to eq(subscription.terminated_at.utc.to_s)
+            expect(result).to match_datetime(subscription.terminated_at.utc)
           end
         end
       end
@@ -288,7 +309,7 @@
         end
 
         it 'returns the termination date' do
-          expect(result).to eq(subscription.terminated_at.utc.to_s)
+          expect(result).to match_datetime(subscription.terminated_at.utc)
         end
       end
     end

spec/services/subscriptions/dates/quarterly_service_spec.rb

@@ -222,14 +222,14 @@
         end
 
         it 'returns the termination date' do
-          expect(result).to eq(subscription.terminated_at.utc.to_s)
+          expect(result).to match_datetime(subscription.terminated_at.utc)
         end
 
         context 'with customer timezone' do
           let(:timezone) { 'America/New_York' }
 
           it 'returns the termination date' do
-            expect(result).to eq(subscription.terminated_at.utc.to_s)
+            expect(result).to match_datetime(subscription.terminated_at.utc)
           end
         end
       end
@@ -295,7 +295,7 @@
         end
 
         it 'returns the termination date' do
-          expect(result).to eq(subscription.terminated_at.utc.to_s)
+          expect(result).to match_datetime(subscription.terminated_at.utc)
         end
       end
     end

spec/services/subscriptions/dates/weekly_service_spec.rb

@@ -159,14 +159,14 @@
         end
 
         it 'returns the termination date' do
-          expect(result).to eq(subscription.terminated_at.utc.to_s)
+          expect(result).to match_datetime(subscription.terminated_at.utc)
         end
 
         context 'with customer timezone' do
           let(:timezone) { 'America/New_York' }
 
           it 'returns the termination date' do
-            expect(result).to eq(subscription.terminated_at.utc.to_s)
+            expect(result).to match_datetime(subscription.terminated_at.utc)
           end
         end
       end
@@ -197,7 +197,7 @@
         end
 
         it 'returns the termination date' do
-          expect(result).to eq(subscription.terminated_at.utc.to_s)
+          expect(result).to match_datetime(subscription.terminated_at.utc)
         end
       end
     end

spec/services/subscriptions/dates/yearly_service_spec.rb

@@ -181,14 +181,14 @@
         end
 
         it 'returns the termination date' do
-          expect(result).to eq(subscription.terminated_at.utc.to_s)
+          expect(result).to match_datetime(subscription.terminated_at.utc)
         end
 
         context 'with customer timezone' do
           let(:timezone) { 'America/New_York' }
 
           it 'returns the termination date' do
-            expect(result).to eq(subscription.terminated_at.utc.to_s)
+            expect(result).to match_datetime(subscription.terminated_at.utc)
           end
         end
       end
@@ -246,7 +246,7 @@
         end
 
         it 'returns the termination date' do
-          expect(result).to eq(subscription.terminated_at.utc.to_s)
+          expect(result).to match_datetime(subscription.terminated_at.utc)
         end
       end
     end