Test-Driven Development overview

Test-Driven Development as a cross-cutting topic - the red-green-refactor cycle of writing a failing test before implementation code, making it pass with minimal code, then refactoring to improve structure. Covers TDD at unit and acceptance levels, outside-in vs inside-out approaches, and the design feedback that emerges from writing tests first. Addresses when TDD provides the highest return and where alternative testing strategies may be more appropriate.