Taking an exam after your studies or your stay in an German speaking country is your chance to validate what you learnt while you were abroad and come back home with an official certificate guaranteeing your ability to communicate in German, and giving you better study or job prospects.
TestDaf - Deutsch als Fremdsprache (German as a Foreign Language Diploma)
The German as a Foreign Language examination, or 'TestDaf' as it is known, allows you to gain direct entry to a German University. The course comprises of 20 lessons per week on the General German group course plus intensive individual preparation each week. The exam dates are fixed by the TestDaF institute and there are identical tests on the same dates all over the world (every two months).