Re-raise 'root' user error in desire app handler

* If not re-raised, error is supressed with no clear user feedback

Author: acosta11

lib/cloud_controller/diego/desire_app_handler.rb

@@ -12,6 +12,8 @@ def create_or_update_app(process, client)
               if e.name == 'RunnerError' && e.message['the requested resource already exists']
                 existing_lrp = client.get_app(process)
                 client.update_app(process, existing_lrp)
+              elsif e.name == 'RunnerError' && e.message["'root' user not permitted"]
+                raise
               end
             end
           end

spec/unit/lib/cloud_controller/diego/desire_app_handler_spec.rb

@@ -51,6 +51,17 @@ module Diego
             expect(client).to have_received(:get_app).exactly(2).times
           end
         end
+
+        context 'when root user is not permitted' do
+          it 'raises a CloudController::Errors::ApiError' do
+            allow(client).to receive(:desire_app).and_raise(CloudController::Errors::ApiError.new_from_details('RunnerError', "'root' user not permitted"))
+            expect { DesireAppHandler.create_or_update_app(process, client) }.to(raise_error do |error|
+              expect(error).to be_a(CloudController::Errors::ApiError)
+              expect(error.name).to eq('RunnerError')
+              expect(error.message).to include(/'root' user not permitted/)
+            end)
+          end
+        end
       end
     end
   end