Record invalid payment states for debugging

We observed invalid payment states in Bugsnag but we don't actually know
in which state the payment intent was in. From the context we can guess
that it was "succeeded" but it would be good to validate this. And in
the future it would be good to know if there are other invalid states we
can end up in.

The notification to Bugsnag happens in another part of the code.

config/locales/en.yml

@@ -294,7 +294,7 @@ en:
   error: Error
   processing_payment: "Processing payment..."
   no_pending_payments: "No pending payments"
-  invalid_payment_state: "Invalid payment state"
+  invalid_payment_state: "Invalid payment state: %{state}"
   filter_results: Filter Results
   quantity: Quantity
   pick_up: Pick up

lib/stripe/payment_intent_validator.rb

@@ -23,9 +23,10 @@ module Stripe
     end
 
     def raise_if_not_in_capture_state(payment_intent_response)
-      return unless payment_intent_response.status != 'requires_capture'
+      state = payment_intent_response.status
+      return unless state != 'requires_capture'
 
-      raise Stripe::StripeError, I18n.t(:invalid_payment_state)
+      raise Stripe::StripeError, I18n.t(:invalid_payment_state, state: state)
     end
   end
 end

spec/lib/stripe/payment_intent_validator_spec.rb

@@ -40,7 +40,7 @@ module Stripe
         it "raises Stripe error with an invalid_payment_state message" do
           expect {
             validator.call(payment_intent_id, stripe_account_id)
-          }.to raise_error Stripe::StripeError, "Invalid payment state"
+          }.to raise_error Stripe::StripeError, "Invalid payment state: failed"
         end
       end
 

spec/models/spree/gateway/stripe_sca_spec.rb

@@ -39,6 +39,16 @@ describe Spree::Gateway::StripeSCA, type: :model do
 
       expect(response.success?).to eq true
     end
+
+    it "provides an error message to help developer debug" do
+      stub_request(:get, "https://api.stripe.com/v1/payment_intents/12345").
+        to_return(status: 200, body: capture_successful)
+
+      response = subject.purchase(order.total, credit_card, gateway_options)
+
+      expect(response.success?).to eq false
+      expect(response.message).to eq "Invalid payment state: succeeded"
+    end
   end
 
   def payment_intent(amount, status)