We've reached the midway point in this year's Google Summer of Code.
The student with whom I am working, Mohamed Nufail of the University of Moratuwa in Sri Lanka, has been working with the Apache Derby team on improving our regression test suites.
As Apache Derby is an extremely sophisticated and mature DBMS implementation, thorough and detailed regression testing is extremely important to the community.
We've been using several code coverage tools, named Emma and JaCoCo, to try to evaluate and improve the quality of our regression test suites.
Currently, we're deep in a puzzling problem which started out as an apparent gap in our test suites (we weren't covering the client-server aspects of JDBC4 testing thoroughly), but might additionally reveal either a bug in Derby's test automation or perhaps even a bug in the Emma tool. Certain classes are clearly invoked by the test suites (we can see output from print statements in the class's methods in the test output), yet Emma reporting is claiming that the class's code was not run.
That's the way it is with software: you start out looking for something, then you find something, and then when you dig into it, it becomes still more interesting!
A great thing about GSoC is that it provides an opportunity for interested young computer scientists to get involved with complex and intricate pieces of software (e.g., Apache Derby) in the framework of an established team that works together cooperatively to improve that software (e.g., the Apache Derby development community), and thus helps bring real-world experience to the academic process.