Add spec test for Default Container Image Rate

spec/models/chargeback_rate_spec.rb

@@ -56,6 +56,14 @@
       expect(cbr.errors.first).to include("default rate cannot be deleted")
     end
 
+    it "when non-default with default description" do
+      cbr = FactoryGirl.create(:chargeback_rate, :description => "Default Container Image Rate", :default => false)
+      cbr.destroy
+      expect(cbr).to_not be_destroyed
+      expect(cbr.errors.count).to be(1)
+      expect(cbr.errors.first).to include("default rate cannot be deleted")
+    end
+
     it "when non-default" do
       cbr = FactoryGirl.create(:chargeback_rate, :description => "Non-default", :default => false)
       cbr.destroy