Add spec for failing Paypal checkout

https://github.com/openfoodfoundation/openfoodnetwork/issues/4233

spec/features/consumer/shopping/checkout_paypal_spec.rb

@@ -0,0 +1,90 @@
+require "spec_helper"
+
+feature "Checking out with Paypal", js: true do
+  include ShopWorkflow
+  include CheckoutWorkflow
+
+  let(:distributor) { create(:distributor_enterprise) }
+  let(:supplier) { create(:supplier_enterprise) }
+  let(:product) { create(:simple_product, supplier: supplier) }
+  let(:variant) { product.variants.first }
+  let(:order_cycle) {
+    create(
+      :simple_order_cycle,
+      suppliers: [supplier],
+      distributors: [distributor],
+      coordinator: distributor,
+      variants: [variant]
+    )
+  }
+  let(:order) {
+    create(
+      :order,
+      order_cycle: order_cycle,
+      distributor: distributor,
+      bill_address_id: nil,
+      ship_address_id: nil
+    )
+  }
+  let(:free_shipping) { create(:shipping_method) }
+  let!(:paypal) do
+    Spree::Gateway::PayPalExpress.create!(
+      name: "Paypal",
+      environment: "test",
+      distributor_ids: [distributor.id]
+    )
+  end
+
+  before do
+    distributor.shipping_methods << free_shipping
+    set_order order
+    add_product_to_cart order, product
+  end
+
+  describe "as a guest" do
+    it "fails with an error message" do
+      pending "The checkout_state_path is missing."
+
+      visit checkout_path
+      complete_the_form
+
+      paypal_response = double(:response, success?: false, errors: [])
+      paypal_provider = double(
+        :provider,
+        build_set_express_checkout: nil,
+        set_express_checkout: paypal_response
+      )
+      allow_any_instance_of(Spree::PaypalController).to receive(:provider).
+        and_return(paypal_provider)
+
+      place_order
+      expect(page).to have_content "PayPal failed."
+    end
+  end
+
+  def complete_the_form
+    checkout_as_guest
+
+    within "#details" do
+      fill_in "First Name", with: "Will"
+      fill_in "Last Name", with: "Marshall"
+      fill_in "Email", with: "test@test.com"
+      fill_in "Phone", with: "0468363090"
+    end
+
+    within "#billing" do
+      fill_in "City", with: "Melbourne"
+      fill_in "Postcode", with: "3066"
+      fill_in "Address", with: "123 Your Head"
+      select "Australia", from: "Country"
+      select "Victoria", from: "State"
+    end
+
+    within "#shipping" do
+      choose free_shipping.name
+    end
+    within "#payment" do
+      choose paypal.name
+    end
+  end
+end