Rails rspec控制器测试用于添加Rest调用的详细信息

I was just wondering if I only have to test the outcome of the controller method rather than internal set. For example, now I have this method in the controller to add detail via a rest call to the backend and then render to the fruit detail partial page. I have to test the render_template but other than that is there anyway to test out the internal rest call response code or object ?I was just wondering if I only have to test the