Spring_puzzles is a project mainly written in Java, it's free.
Puzzles for the Spring Framework presented with Sergi Almar (@sergialmar) at the Spring I/O 2011
Spring puzzles is a collection of common Spring pitfalls.
In the project we show common mistakes often found in Spring apps. We cover samples from Spring Core, Spring AOP, Spring Testing and Spring Transactions. The project is build using gradle and we have a test per each puzzle, found in src/main/test