Add StripeCreditCard#try_void

This method is now the preferred way in Solidus for canceling a payment
and supersedes the old #cancel method.

If a payment for a Payment Intent was captured, it cannot be cancelled
anymore, but needs to be refunded.
For this refund we're using the default order cancel reason named after
`Spree::Payment::Cancellation::DEFAULT_REASON`.

app/models/spree/payment_method/stripe_credit_card.rb

@@ -81,6 +81,21 @@ def void(response_code, _creditcard, _transaction_options)
         gateway.void(response_code, {})
       end
 
+      def payment_intents_refund_reason
+        Spree::RefundReason.where(name: Spree::Payment::Cancellation::DEFAULT_REASON).first_or_create
+      end
+
+      def try_void(payment)
+        if v3_intents? && payment.completed?
+          payment.refunds.create!(
+            amount: payment.credit_allowed,
+            reason: payment_intents_refund_reason
+          ).response
+        else
+          payment.void_transaction!
+        end
+      end
+
       def cancel(response_code)
         gateway.void(response_code, {})
       end

spec/models/spree/payment_method/stripe_credit_card_spec.rb

@@ -22,7 +22,8 @@
   let(:payment) {
     double('Spree::Payment',
       source: source,
-      order: order
+      order: order,
+      amount: order.total
     )
   }
 
@@ -241,4 +242,46 @@
       expect(gateway).to receive(:capture).with(9855, '12345', anything).and_return(success_response)
     end
   end
+
+  describe '#try_void' do
+    let(:payment) { create :payment, amount: order.total }
+
+    shared_examples 'voids the payment transaction' do
+      it 'voids the payment transaction' do
+        expect(payment).to receive(:void_transaction!)
+
+        subject.try_void(payment)
+      end
+    end
+
+    context 'when using Payment Intents' do
+      before { subject.preferred_v3_intents = true }
+
+      context 'when the payment is completed' do
+        before do
+          allow(payment).to receive(:completed?) { true }
+        end
+
+        it 'creates a refund' do
+          expect { subject.try_void(payment) }.to change { Spree::Refund.count }.by(1)
+        end
+      end
+
+      context 'when the payment is not completed' do
+        it_behaves_like 'voids the payment transaction'
+      end
+    end
+
+    context 'when not using Payment Intents' do
+      before { subject.preferred_v3_intents = false }
+
+      context 'when the payment is completed' do
+        it_behaves_like 'voids the payment transaction'
+      end
+
+      context 'when the payment is not completed' do
+        it_behaves_like 'voids the payment transaction'
+      end
+    end
+  end
 end