Log a warning on cache MISS

lib/open_food_network/cached_products_renderer.rb

@@ -13,6 +13,8 @@ module OpenFoodNetwork
 
     def products_json
       products_json = Rails.cache.fetch("products-json-#{@distributor.id}-#{@order_cycle.id}") do
+        log_warning
+
         begin
           uncached_products_json
         rescue ProductsRenderer::NoProducts
@@ -28,6 +30,12 @@ module OpenFoodNetwork
 
     private
 
+    def log_warning
+      if Rails.env.production? || Rails.env.staging?
+        Bugsnag.notify RuntimeError.new("Live server MISS on products cache for distributor: #{@distributor.id}, order cycle: #{@order_cycle.id}")
+      end
+    end
+
     def uncached_products_json
       ProductsRenderer.new(@distributor, @order_cycle).products_json
     end

spec/lib/open_food_network/cached_products_renderer_spec.rb

@@ -41,6 +41,11 @@ module OpenFoodNetwork
           cpr.products_json
           expect(cached_json).to eq 'fresh products'
         end
+
+        it "logs a warning" do
+          cpr.should_receive :log_warning
+          cpr.products_json
+        end
       end
 
       describe "when there are no products" do
@@ -55,13 +60,31 @@ module OpenFoodNetwork
           expect(cache_present).to be
           expect(cached_json).to be_nil
         end
+
+        it "logs a warning" do
+          cpr.should_receive :log_warning
+          expect { cpr.products_json }.to raise_error ProductsRenderer::NoProducts
+        end
+      end
+    end
+
+    describe "logging a warning" do
+      it "logs a warning when in production" do
+        Rails.env.stub(:production?) { true }
+        expect(Bugsnag).to receive(:notify)
+        cpr.send(:log_warning)
       end
 
-      describe "logging a warning" do
-        it "logs a warning when in production"
-        it "logs a warning when in staging"
-        it "does not log a warning in development"
-        it "does not log a warning in test"
+      it "logs a warning when in staging" do
+        Rails.env.stub(:production?) { false }
+        Rails.env.stub(:staging?) { true }
+        expect(Bugsnag).to receive(:notify)
+        cpr.send(:log_warning)
+      end
+
+      it "does not log a warning in development or test" do
+        expect(Bugsnag).to receive(:notify).never
+        cpr.send(:log_warning)
       end
     end