Move pre-selection test for belongs to case to end-to-end spec

Kept getting error of the form

    undefined method `admin_product_product_variant_path' for
    #<Admin::VariantsController>

when trying execute the test as part of the request spec. When running
the test individually everything worked, but once the end-to-end test
had run, the error occurred. I therefore suspect this might be caused
by setting up the nested Active Admin resources twice.

Testing both cases as part of the end-to-end spec helps work around
the problem.

Author: tf

spec/features/ajax_params_spec.rb

@@ -50,52 +50,4 @@
     expect(response.body).to have_selector('.searchable-select-input' \
                                            "[data-ajax-url*='#{url_matcher}']")
   end
-
-  context 'when using belongs_to' do
-    before(:each) do
-      ActiveAdminHelpers.setup do
-
-        ActiveAdmin.register(OptionType)
-
-        ActiveAdmin.register(Product) do
-
-        ActiveAdmin.register(OptionValue) do
-          belongs_to :option_type
-          searchable_select_options(scope: lambda do |params|
-                                            OptionValue.where(
-                                              option_type_id: params[:option_type_id]
-                                            )
-                                          end,
-                                    text_attribute: :value)
-        end
-
-        ActiveAdmin.register(Variant) do
-          belongs_to :product
-        
-          form do |f|
-            f.input(:option_value,
-                    as: :searchable_select,
-                    ajax: {
-                      resource: OptionValue,
-                      path_params: {
-                        option_type_id: f.object.product.option_type_id
-                      }
-                    })
-          end
-        end
-      end
-    end
-
-    it 'pre-select items in the associations' do 
-      option_type = OptionType.create
-      product = Product.create(option_type: option_type)
-      option_value = OptionValue.create(option_type: option_type, value: 'Red')
-      variant = Variant.create(product: product, option_value: option_value)
-
-      get "/admin/products/#{product.id}/variants/#{variant.id}/edit"
-  
-      expect(response.body).to have_selector('.searchable-select-input option[selected]',
-        count: 1)
-    end
-  end
 end

spec/features/end_to_end_spec.rb

@@ -180,6 +180,22 @@
         expect(select_box_items.size).to eq(15)
       end
     end
+
+    describe 'edit page with searchable select filter' do
+      it 'preselects item' do
+        option_type = OptionType.create(name: 'Color')
+        ot = OptionType.create(name: 'Size')
+        option_value = OptionValue.create(value: 'Black', option_type: option_type)
+        OptionValue.create(value: 'Orange', option_type: option_type)
+        OptionValue.create(value: 'M', option_type: ot)
+        product = Product.create(name: 'Cap', option_type: option_type)
+        variant = Variant.create(product: product, option_value: option_value)
+
+        visit "/admin/products/#{product.id}/variants/#{variant.id}/edit"
+
+        expect(select_box_selected_item_text).to eq('Black')
+      end
+    end
   end
 
   def expand_select_box
@@ -198,6 +214,10 @@ def select_box_items
     all('.select2-dropdown li').map(&:text)
   end
 
+  def select_box_selected_item_text
+    find('.select2-selection').text
+  end
+
   def wait_for_ajax
     Timeout.timeout(Capybara.default_max_wait_time) do
       sleep 0.1