Whatever level of German you choose to study, examinations will be part of the package
In all cases, there will be a combination of listening, speaking, and written components. At A1 and A2 levels, the examinations won't be particularly difficult, and the questions should be extremely simple. A2 differs from A1 by having slightly more in-depth questions, and the need to use or comprehend longer words in more complex sentences.
At B1 level, students will need a vocabulary of over 2,000 words, knowledge of clauses, a strong grasp of sentence structure, and the ability to understand spoken German at TV or movie speeds.
B2 is similar to B1, but with a much tighter emphasis on speaking about German life. Knowledge of German culture, politics, and economics may help here. And the level of accuracy required is taken up a notch, as well.
C1 requires almost fluency in speaking and writing German, so at this stage it's advisable to immerse yourself in German language. Practice makes perfect here, both for tightening up sentences, and mastering complex listening tasks.
Finally, C2 takes C1 to another level, with extended essays and a need to come across like a native German. At that stage, students should be virtually fluent.
Preparation is everything when taking language exams. To get a feel for what is required, head to the Goethe Institut, and use their specimen papers.