Topic: How to test call of "render_component"

I'm quite new to RoR and try to develop my first app with it. I developed a controller + view which I include as a component because I want to use the functionality in different parts of my app. I included the component with the call "render_component". It works fine - the view looks correct. But I want to develop a test for that include. When I test a view I test if there is a textfield with a specific name and ID, if it contains a table and so on... But how can I test whether "render_component" is called correctly?
Thanks for your help!