Only show fields for calculators that we have preference form fields for

We do not ship preference form fields for Array and Hash preference types. Some shipping or tax rate calculators might use them to store very specific settings. As arrays and hashes won't represent well in a form field, we should not render them.

backend/app/views/spree/admin/shared/_calculator_fields.html.erb

@@ -11,9 +11,10 @@
       <% calculator = f.object.calculator.class == calculator_class ? f.object.calculator : calculator_class.new %>
       <div class="js-calculator-preferences" data-calculator-type="<%= calculator_class %>">
         <%= f.fields_for :calculator, calculator do |calculator_form| %>
-          <% calculator.preferences.keys.each do |key| %>
-            <%= render "spree/admin/shared/preference_fields/#{calculator.preference_type(key)}",
-               form: calculator_form, attribute: "preferred_#{key}", label: t(key, scope: 'spree') %>
+          <% calculator.admin_form_preference_names.each do |name| %>
+            <%= render "spree/admin/shared/preference_fields/#{calculator.preference_type(name)}",
+              form: calculator_form, attribute: "preferred_#{name}",
+              label: t(name, scope: 'spree', default: name.to_s.humanize) %>
           <% end %>
         <% end %>
       </div>

backend/spec/features/admin/configuration/shipping_methods_spec.rb

@@ -35,6 +35,46 @@
       click_on "Create"
       expect(current_path).to eql(spree.edit_admin_shipping_method_path(Spree::ShippingMethod.last))
     end
+
+    context 'with shipping method having a calculator with array or hash preference type' do
+      before do
+        class ComplexShipments < Spree::ShippingCalculator
+          preference :amount, :decimal
+          preference :currency, :string
+          preference :mapping, :hash
+          preference :list, :array
+
+          def self.description
+            "Complex Shipments"
+          end
+        end
+        @calculators = Rails.application.config.spree.calculators.shipping_methods
+        Rails.application.config.spree.calculators.shipping_methods = [ComplexShipments]
+      end
+
+      after do
+        Rails.application.config.spree.calculators.shipping_methods = @calculators
+      end
+
+      it "does not show array and hash form fields" do
+        click_link "New Shipping Method"
+
+        fill_in "shipping_method_name", with: "bullock cart"
+
+        within("#shipping_method_categories_field") do
+          check first("input[type='checkbox']")["name"]
+        end
+
+        click_on "Create"
+        select 'Complex Shipments', from: 'Base Calculator'
+        click_on "Update"
+
+        expect(page).to have_field('Amount')
+        expect(page).to have_field('Currency')
+        expect(page).to_not have_field('Mapping')
+        expect(page).to_not have_field('List')
+      end
+    end
   end
 
   # Regression test for https://github.com/spree/spree/issues/1331