After digging through the internet for a couples of days, searching for a valid resource of a project using AngularJS with require.js and a running Testacular configuration, I finally found a helpful resource in this highly useful blog article (http://entwicklertagebuch.com/blog/2013/01/angularjs-app-mit-requirejs-und-testacular-testen/).
Finally after a couple of chats, Marco showed me the reasons why my intial project setup did not work out of the box. Thanks a lot again!