#425

backend/spec/support/tag_group_records.rb

@@ -34,6 +34,37 @@ module TagGroupRecords
     WRITE_TABLES.to_h { |table| [table, group_rows(table)] }
   end
 
+  def expect_noop_group_update group_id:, page:
+    before_state = group_state
+    group = TagGroup.find(group_id)
+    version_id = TagGroupVersion.find_by!(
+        tag_group_id: group_id, version_no: group.version_no).id
+    revision_id = page.reload.current_revision.id
+    wiki_version_id = page.wiki_versions.order(version_no: :desc).first.id
+    writes = []
+    tables = Regexp.union(WRITE_TABLES)
+    subscriber = lambda do |*args|
+      sql = args.last.fetch(:sql)
+      if sql.match?(/\A\s*(?:INSERT INTO|UPDATE|DELETE FROM)\s+`?(?:#{ tables })`?\s/i)
+        writes << sql
+      end
+    end
+
+    aggregate_failures 'no-op current state, history and SQL writes' do
+      ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') { yield }
+      expect(response).to have_http_status(:ok)
+      after_state = group_state
+      before_state.each do |table, rows|
+        expect(after_state.fetch(table)).to eq(rows), "No-op changed #{ table }"
+      end
+      expect(TagGroupVersion.find_by!(
+          tag_group_id: group_id, version_no: group.reload.version_no).id).to eq(version_id)
+      expect(page.reload.current_revision.id).to eq(revision_id)
+      expect(page.wiki_versions.order(version_no: :desc).first.id).to eq(wiki_version_id)
+      expect(writes).to be_empty
+    end
+  end
+
   def expect_atomic_group_write table
     before_state = group_state
     failure = Class.new(StandardError)