mailer-demo

This is an example of a simple app to send email, written to demonstrate Outside-In TDD guiding the engineer to using the Interface and Adapter pattern. The first iterations are done "test-after". When we switch to TDD, the design pattern is obvious, and allows us to make the application much more maintainble when the third party service we built it around is no longer usable.

• Phase 1: Test-After Approach
• Phase 2: Use Dependency Injection to allow an Isolated Test
• Phase 3: TDD - Interface & Adapter
• Phase 4: Handling Change by Adapters