Improve scope_variant_to_hub code and spec by testing an invalid data state

app/models/variant_override.rb

@@ -62,6 +62,10 @@ class VariantOverride < ActiveRecord::Base
     count_on_hand.present?
   end
 
+  def use_producer_settings?
+    on_demand.nil?
+  end
+
   def decrement_stock!(quantity)
     if stock_overridden?
       decrement! :count_on_hand, quantity

lib/open_food_network/scope_variant_to_hub.rb

@@ -29,15 +29,19 @@ module OpenFoodNetwork
       end
 
       def count_on_hand
-        return super unless @variant_override.andand.stock_overridden?
-
-        @variant_override.count_on_hand
+        if @variant_override.present? && @variant_override.stock_overridden?
+          @variant_override.count_on_hand
+        else
+          super
+        end
       end
 
       def on_demand
-        return super if @variant_override.andand.on_demand.nil?
-
-        @variant_override.andand.on_demand
+        if @variant_override.present? && !@variant_override.use_producer_settings?
+          @variant_override.on_demand
+        else
+          super
+        end
       end
 
       def decrement!(attribute, by = 1)

spec/lib/open_food_network/scope_variant_to_hub_spec.rb

@@ -82,13 +82,6 @@ module OpenFoodNetwork
           context "without an on_demand set" do
             before { vo.update_column(:on_demand, nil) }
 
-            context "when count_on_hand is set" do
-              it "returns variant's on_demand" do
-                scoper.scope v
-                expect(v.on_demand).to be true
-              end
-            end
-
             context "when count_on_hand is not set" do
               before { vo.update_column(:count_on_hand, nil) }
 
@@ -97,6 +90,13 @@ module OpenFoodNetwork
                 expect(v.on_demand).to be true
               end
             end
+
+            context "when count_on_hand is set" do
+              it "should return validation error on save" do
+                scoper.scope v
+                expect{ vo.save! }.to raise_error ActiveRecord::RecordInvalid
+              end
+            end
           end
         end