Refresh products cache when exchange fee is changed or destroyed

app/models/exchange_fee.rb

@@ -1,4 +1,15 @@
 class ExchangeFee < ActiveRecord::Base
   belongs_to :exchange
   belongs_to :enterprise_fee
+
+
+  after_save :refresh_products_cache
+  after_destroy :refresh_products_cache
+
+
+  private
+
+  def refresh_products_cache
+    exchange.refresh_products_cache
+  end
 end

spec/models/exchange_fee_spec.rb

@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe ExchangeFee do
+  describe "products caching" do
+    let(:exchange) { create(:exchange) }
+    let(:enterprise_fee) { create(:enterprise_fee) }
+
+    it "refreshes the products cache on change" do
+      expect(OpenFoodNetwork::ProductsCache).to receive(:exchange_changed).with(exchange)
+      exchange.enterprise_fees << enterprise_fee
+    end
+
+    it "refreshes the products cache on destruction" do
+      exchange.enterprise_fees << enterprise_fee
+      expect(OpenFoodNetwork::ProductsCache).to receive(:exchange_changed).with(exchange)
+      exchange.reload.exchange_fees.destroy_all
+    end
+  end
+end