The on-site test was in Java, they provide you with a set of classes, abstract classes, interfaces and JUnit tests asking a few implementation questions. First you have understand and sketch the hierarchy of the project classes, then you need to modify a few methods to comply with the given JUnit tests that fail, then you need to implement a few new methods and the corresponding JUnit tests, and finally a few more code implementations. Another question was to reproduce a specific bug, find the fix the problem in the code. Overall it consisted of 7-8 questions and was quite interesting but intense for the given 2 hours and 30 minutes. Although there was no pressure or requirement to finish everything on-time.