Assessment is one of the major factors to consider when developing a new course or program of study. When developing a course to teach Computer Science there are many forms this could take, one of which is linked to Computational Thinking. Whilst developing Computer Science to Go (CS2Go), an introductory course aimed at secondary school students, we have developed a Computational Thinking test based on the problems developed for the international Bebras Challenge. This paper will describe the content and development of the course, as well as some analysis on results from a year-long study with secondary school students and first-year undergraduate students. We believe that, based on our analysis and previous research in the field, that our assessment, based on pre-exisiting Bebras problems, has the potential to offer educators another way of testing this increasingly discussed skill, Computational Thinking.