Add automated tests around pagination in product list for a shop

- with two order cycles and go from one to the other

spec/features/consumer/shopping/shopping_spec.rb

@@ -159,6 +159,31 @@ feature "As a consumer I want to shop with a distributor", js: true do
             end
           end
         end
+
+        describe "two order cycles and more than 20 products for each" do
+          before do
+            20.times do
+              product = create(:simple_product, supplier: supplier)
+              add_variant_to_order_cycle(exchange1, product.variants.first)
+              add_variant_to_order_cycle(exchange2, product.variants.first)
+            end
+          end
+
+          it "show the whole products list for each OC" do
+            visit shop_path
+            select "turtles", from: "order_cycle_id"
+            select "frogs", from: "order_cycle_id"
+            expect(page).to have_selector("product", count: 10)
+            scroll_to(page.find(".product-listing"), align: :bottom)
+            expect(page).to have_selector("product", count: 20)
+
+            scroll_to(page.find("distributor"))
+            select "turtles", from: "order_cycle_id"
+            expect(page).to have_selector("product", count: 10)
+            scroll_to(page.find(".product-listing"), align: :bottom)
+            expect(page).to have_selector("product", count: 20)
+          end
+        end
       end
     end