Trigger products cache refresh when enterprise fee changed or destroyed

app/models/enterprise_fee.rb

@@ -2,10 +2,11 @@ class EnterpriseFee < ActiveRecord::Base
   belongs_to :enterprise
   belongs_to :tax_category, class_name: 'Spree::TaxCategory', foreign_key: 'tax_category_id'
   has_and_belongs_to_many :order_cycles, join_table: 'coordinator_fees'
-  has_many :exchange_fees, dependent: :destroy
+  has_many :exchange_fees
   has_many :exchanges, through: :exchange_fees
 
-  before_destroy { order_cycles.clear }
+  after_save :refresh_products_cache
+  around_destroy :destruction
 
   calculated_adjustments
 
@@ -57,4 +58,25 @@ class EnterpriseFee < ActiveRecord::Base
                                 :mandatory => mandatory,
                                 :locked => true}, :without_protection => true)
   end
+
+
+  private
+
+  def refresh_products_cache
+    OpenFoodNetwork::ProductsCache.enterprise_fee_changed self
+  end
+
+  def destruction
+    OpenFoodNetwork::ProductsCache.enterprise_fee_destroyed(self) do
+      # Remove this association here instead of using dependent: :destroy because
+      # dependent-destroy acts before this around_filter is called, so ProductsCache
+      # has no way of knowing where this fee was used.
+      order_cycles.clear
+      exchange_fees.destroy_all
+
+      # Destroy the enterprise fee
+      yield
+    end
+
+  end
 end

lib/open_food_network/products_cache.rb

@@ -49,6 +49,15 @@ module OpenFoodNetwork
     end
 
 
+    def self.enterprise_fee_changed(enterprise_fee)
+    end
+
+
+    def self.enterprise_fee_destroyed(enterprise_fee, &block)
+      block.call
+    end
+
+
     private
 
     def self.exchanges_featuring_variants(variants, distributor: nil)

spec/models/enterprise_fee_spec.rb

@@ -10,8 +10,20 @@ describe EnterpriseFee do
   end
 
   describe "callbacks" do
+    let(:ef) { create(:enterprise_fee) }
+
+    it "refreshes the products cache when saved" do
+      expect(OpenFoodNetwork::ProductsCache).to receive(:enterprise_fee_changed).with(ef)
+      ef.name = 'foo'
+      ef.save
+    end
+
+    it "refreshes the products cache when destroyed" do
+      expect(OpenFoodNetwork::ProductsCache).to receive(:enterprise_fee_destroyed).with(ef)
+      ef.destroy
+    end
+
     it "removes itself from order cycle coordinator fees when destroyed" do
-      ef = create(:enterprise_fee)
       oc = create(:simple_order_cycle, coordinator_fees: [ef])
 
       ef.destroy
@@ -19,7 +31,6 @@ describe EnterpriseFee do
     end
 
     it "removes itself from order cycle exchange fees when destroyed" do
-      ef = create(:enterprise_fee)
       oc = create(:simple_order_cycle)
       ex = create(:exchange, order_cycle: oc, enterprise_fees: [ef])