Update Stripe payment intents decorator

- copied the relevant code from the new Active Merchant version
- Add spec to cover the scenario of saving a card when paying by card
- Fix Stripe stub.

I used stripe stubs for the new scenario because storing a card on
stripe depends on some client side interaction with Stripe. We can't
capture that with VCR.

lib/active_merchant/billing/gateways/stripe_payment_intents_decorator.rb

@@ -38,9 +38,9 @@ ActiveMerchant::Billing::StripePaymentIntentsGateway.class_eval do
   end
 
   # Note: Not all payment methods are currently supported by the
-  #   {Payment Methods API}[https://stripe.com/docs/payments/payment-methods]
-  # Current implementation will create
-  #   a PaymentMethod object if the method is a token or credit card
+  #     {Payment Methods API}[https://stripe.com/docs/payments/payment-methods]
+  # Current implementation will create a PaymentMethod object if the method is a token
+  #     or credit card
   # All other types will default to legacy Stripe store
   def store(payment_method, options = {})
     params = {}
@@ -48,27 +48,15 @@ ActiveMerchant::Billing::StripePaymentIntentsGateway.class_eval do
 
     # If customer option is provided, create a payment method and attach to customer id
     # Otherwise, create a customer, then attach
-    # if payment_method.is_a?(StripePaymentToken) ||
-    #   payment_method.is_a?(ActiveMerchant::Billing::CreditCard)
-    add_payment_method_token(params, payment_method, options)
-    if options[:customer]
-      customer_id = options[:customer]
-    else
-      post[:validate] = options[:validate] unless options[:validate].nil?
-      post[:description] = options[:description] if options[:description]
-      post[:email] = options[:email] if options[:email]
-      customer = commit(:post, 'customers', post, options)
-      customer_id = customer.params['id']
+    result = add_payment_method_token(params, payment_method, options)
+    return result if result.is_a?(ActiveMerchant::Billing::Response)
 
-      # return the stripe response if expected customer id is not present
-      return customer if customer_id.nil?
-    end
-    commit(:post,
-           "payment_methods/#{params[:payment_method]}/attach",
-           { customer: customer_id }, options)
-    # else
-    #   super(payment, options)
-    # end
+    customer_id = options[:customer] || customer(post, payment_method, options).params['id']
+    options = format_idempotency_key(options, 'attach')
+    attach_parameters = { customer: customer_id }
+    attach_parameters[:validate] = options[:validate] unless options[:validate].nil?
+
+    commit(:post, "payment_methods/#{params[:payment_method]}/attach", attach_parameters, options)
   end
 
   private

spec/support/request/stripe_stubs.rb

@@ -44,7 +44,7 @@ module StripeStubs
   # Stubs the customers call to both the main stripe account and the connected account
   def stub_customers_post_request(email:, response: {}, stripe_account_header: false)
     stub = stub_request(:post, "https://api.stripe.com/v1/customers")
-      .with(body: { email: })
+      .with(body: { expand: ["sources"], email: })
     stub = stub.with(headers: { 'Stripe-Account' => 'abc123' }) if stripe_account_header
     stub.to_return(customers_response_mock(response))
   end

spec/system/consumer/checkout/payment_spec.rb

@@ -250,6 +250,25 @@ describe "As a consumer, I want to checkout my order" do
               click_on "Next - Order summary"
               proceed_to_summary
             end
+
+            context "when saving card" do
+              it "selects Stripe SCA and proceeds to the summary step" do
+                stub_customers_post_request(email: order.user.email)
+                stub_payment_method_attach_request
+
+                choose pay_method.to_s
+                fill_out_card_details
+                check "Save card for future use"
+
+                click_on "Next - Order summary"
+                proceed_to_summary
+
+                # Verify card has been saved with correct stripe IDs
+                user_credit_card = order.reload.user.credit_cards.first
+                expect(user_credit_card.gateway_payment_profile_id).to eq "pm_123"
+                expect(user_credit_card.gateway_customer_profile_id).to eq "cus_A123"
+              end
+            end
           end
         end