Both insert key and delete key operations are now available. More test cases are being written; in order to test lock conflicts when the same key is concurrently inserted/deleted by different transactions, the new test cases have to use multiple threads. It is harder to debug such test cases, but Eclipse makes it easy. I simply run the JUnit tests in debug mode and set break points at appropriate places.
By end of this week I shall be working on the BTree scan operations. There aren't many research publications that deal with the inner workings of an index scan; the only paper that seems to discuss a real implementation is the paper by Mohan, C. An Efficient Method for Performing Record Deletions and Updates Using Index Scans, Proc. 28th International Conference on Very Large Databases, Hong Kong, August 2002. The paper discusses many of the performance issues with implementing scans. My implementation will suffer from the problems Mohan describes, as I want to do a basic implementation first before looking at optimisations.
To ensure that the BTree implementation is tested thoroughly, I have started to use the code coverage tool Clover. The vendor has graciously provided me a free license to use this tool. Using this tool I am able to determine which code paths have not been tested, and then write test cases to exercise those.