Fix validation of conflicting manifest features

Switching from service-binding-k8s to file-based-vcap-services via
manifest entries (features) raised an error. This change fixes the wrong
validation for this corner case.

Author: philippthun

app/actions/app_feature_update.rb

@@ -30,8 +30,8 @@ def feature_column_name(feature_name)
       end
 
       def check_invalid_combination!(app, flags)
-        file_based_vcap_services_enabled = flags[feature_column_name(AppFeatures::FILE_BASED_VCAP_SERVICES_FEATURE)].present? || app.file_based_vcap_services_enabled
-        service_binding_k8s_enabled = flags[feature_column_name(AppFeatures::SERVICE_BINDING_K8S_FEATURE)].present? || app.service_binding_k8s_enabled
+        file_based_vcap_services_enabled = flags.fetch(feature_column_name(AppFeatures::FILE_BASED_VCAP_SERVICES_FEATURE), app.file_based_vcap_services_enabled)
+        service_binding_k8s_enabled = flags.fetch(feature_column_name(AppFeatures::SERVICE_BINDING_K8S_FEATURE), app.service_binding_k8s_enabled)
         return unless file_based_vcap_services_enabled && service_binding_k8s_enabled
 
         msg = "'#{AppFeatures::FILE_BASED_VCAP_SERVICES_FEATURE}' and '#{AppFeatures::SERVICE_BINDING_K8S_FEATURE}' features cannot be enabled at the same time."

spec/unit/actions/app_feature_update_spec.rb

@@ -122,6 +122,27 @@ module VCAP::CloudController
         end
       end
 
+      context 'when switching from service-binding-k8s to file-based-vcap-services' do
+        before do
+          app.update(service_binding_k8s_enabled: true)
+          features[:'service-binding-k8s'] = false
+          features[:'file-based-vcap-services'] = true
+        end
+
+        it 'updates the corresponding columns in a single database call' do
+          expect(app.service_binding_k8s_enabled).to be(true)
+          expect(app.file_based_vcap_services_enabled).to be(false)
+
+          expect do
+            AppFeatureUpdate.bulk_update(app, message)
+          end.to have_queried_db_times(/update .apps./i, 1)
+
+          app.reload
+          expect(app.service_binding_k8s_enabled).to be(false)
+          expect(app.file_based_vcap_services_enabled).to be(true)
+        end
+      end
+
       context 'when conflicting features are specified' do
         before do
           features[:'service-binding-k8s'] = true