Test Action Models error message for unneeded namespaces (#1102)

* Write test for Action Models error message

* Fixing Standard Ruby

test/system/action_models_test.rb

@@ -39,6 +39,12 @@ def setup
 
   # targets-many action
   if defined?(Projects::ArchiveAction)
+    # This error message is displayed for all actions, not just `targets-many`.
+    test "the proper error message is displayed for unneeded namespaces" do
+      output = `bin/super-scaffold action-model:targets-many Project::Publish Project Team`
+      assert output.include?("When creating an Action Model, you don't have to namespace the action")
+    end
+
     test "developers can archive a single project" do
       login_as(@jane, scope: :user)
       visit account_team_path(@jane.current_team)