How do I design objects using tests

I would like to show how I try to design object and writing OO applications using techniques related with TDD base on simple project on github.

1. How do I design objects using tests @cocoders
2. @cocoders Who I am? Developer, Former medieval reactor, Beer lover and founder of Cocoders
3. Let's imagine legacy app: http://git.io/vLPVa @cocoders
4. Task: Allow company to view incoming and outgoing invoices using system @cocoders
5. The first attempt: http://git.io/vLPre @cocoders Design Invoice object
6. Second attempt (encapsulation): http://git.io/vLPoh @cocoders Design Invoice object
7. Another attempt (ValueObjects): http://git.io/vLPKZ @cocoders Design Invoice object
8. InvoiceRegistry model concept: http://git.io/vLPPq @cocoders Design Model
9. Use important concept in legacy: http://git.io/vLPXc @cocoders Design Model
10. Protect object invariants: http://git.io/vLPXw @cocoders Design Model
11. Implementation of model concept in separate mysql adapter: http://git.io/vLP1D @cocoders Design Model
12. Application layer rely on abstraction: http://git.io/vLPM7 @cocoders Design Application
13. Usage of application object in legacy app: http://git.io/vLPDE @cocoders Design Application
14. Next step: http://git.io/vLPys @cocoders Design Application
15. That's all... for now Thank you @cocoders
16. Questions? @cocoders