Remove line item adjustments if line item deleted

app/models/concerns/line_item_based_adjustment_handling.rb

@@ -0,0 +1,8 @@
+module LineItemBasedAdjustmentHandling
+  extend ActiveSupport::Concern
+
+  included do
+    has_many :adjustments_for_which_source, class_name: "Spree::Adjustment", as: :source,
+                                            dependent: :destroy
+  end
+end

app/models/spree/line_item_decorator.rb

@@ -3,6 +3,7 @@ require 'open_food_network/variant_and_line_item_naming'
 
 Spree::LineItem.class_eval do
   include OpenFoodNetwork::VariantAndLineItemNaming
+  include LineItemBasedAdjustmentHandling
   has_and_belongs_to_many :option_values, join_table: 'spree_option_values_line_items', class_name: 'Spree::OptionValue'
 
   # Redefining here to add the inverse_of option

spec/models/spree/order_spec.rb

@@ -398,7 +398,7 @@ describe Spree::Order do
         expect(order.line_items(:reload).map(&:variant)).to eq([v2])
       end
 
-      pending "removes the variant's adjustment" do
+      it "removes the variant's adjustment" do
         line_item = order.line_items.where(variant_id: v1.id).first
         adjustment_scope = Spree::Adjustment.where(source_type: "Spree::LineItem",
                                                    source_id: line_item.id)