Attempt to spec for error

It didn't catch the error I was looking for. I'm not sure if it is a valid use case, but it still seems helpful to add coverage for current functionality.

spec/controllers/checkout_controller_spec.rb

@@ -328,6 +328,23 @@ RSpec.describe CheckoutController, type: :controller do
             expect_cable_ready_redirect(response)
           end
         end
+
+        context "with existing invalid payments" do
+          let(:invalid_payments) { [
+              create(:payment, state: :failed),
+              create(:payment, state: :void),
+            ] }
+
+          before do
+            order.payments = invalid_payments
+          end
+
+          it "deletes invalid payments" do
+            expect{
+              put(:update, params:)
+            }.to change { order.payments.to_a }.from(invalid_payments)
+          end
+        end
       end
 
       context "with no payment source" do