The code that you are trying to use, replaces default HTML mechanism in Marionette.
- 'template/test.html' will be translated to "/app/templates/template/test.html.html", which I guess is not what you want (Either change url generation, or template pointer)
- Your Backbone code, does not assume, that "test.html" was precompiled on contrary compilation is happening on the client, following GET response, is this what you want?
- Regarding Backbone override use, it should be called before you try to render your ToolItemView, so basically you can call this code anywhere before ToolItemView render.