Architectural TDD

Test-Driven Development is not about testing; it is about Design. It forces you to think about the 'API' of your class from the perspective of the user before you write a single line of implementation.

1. The Red-Green-Refactor Loop

1. Red: Write a test for a feature that doesn't exist. It fails.
2. Green: Write the minimum code to make it pass.
3. Refactor: Clean up the code, remove duplication, and optimize.

2. Why Architects love TDD

TDD naturally leads to **Decoupled Code**. If you write the test first, you are forced to make the class 'Easy to instantiate.' This automatically fixes problems like hidden global dependencies and hard-coded 'new' statements.

4. Interview Mastery

Q: "When is TDD NOT appropriate?"

Architect Answer: "TDD is difficult when the requirements are extremely fluid and you are 'Exploring' the solution. It is also overkill for trivial code (like basic POCO classes or simple UI views). I use TDD for **Core Business Logic**, **Complex Algorithms**, and **Public APIs** where the cost of a mistake is high and the 'API' needs to be perfect."