If I am building a test class for a custom controller, I generally start like this and I dont have any issues:
CustomControllerExtensionNameccn = new CustomControllerExtensionName();
However, as this custom controller is not an extension of a stadard controller, so the VF page will look like this:
apex:page controller="CustomControllerName" extensions="CustomControllerExtensionName"
I cant use this system. After many hours of google I only found examples to test for custom controllers that are extensions of an standard controller, but not for custom controller