Assignment

Task

Try to introduce every single Design Pattern you can think of. The goal is to experiment and play.

Disclaimer: I would discourage such an attitude in production systems, but for learning, try to add in here all the patterns you can imagine.

If lacking ideas, consider:

• Adapter + a new Domain class to return from it
• Implement Dependency Inversion between different packages (move the Adapter in an infra package and use ArchUnit to check that domain does NOT depend on infra)
• Repository encapsulating the (very ugly) raw JDBC access
• Exposing Dtos from your REST API (@GetMapping method), instead of central Entities
• Isolate the filtering rules in a class that only works on structures that I control (that is, in a Domain Service)
• Introduce a Facade to orchestrate the main flow (3-5 lines in its method)
• Factory method
• Decorator around the extracted Adapter that logs every method call
• Proxy if you are brave enough to try implement a Spring @Aspect (with the same goal: logging method calls + parameters) [hard]
• "Manual" singleton around the configuration (despite the wonderful Spring @Value annotation) to avoid re-reading it every time
• Fluent Builder for the Lemon to ease its construction when read from DB
• Observer Pattern to insert the audit "out of band", without direct coupling of our code to it
• Command Pattern/DTO to encapsulate the two input parameters as an object
• Filters that remove (or allow) a Lemon to pass the search criteria

Tests

God smiled upon this project so there is ONE end-to-end smoke test going through all the code. Try to keep it green.

If you want start the app and test it manually:

1. run StartWireMock
2. run LemonApp
3. go to http://localhost:8080/?username=john&gisLocation=abc