tdd

Vertical slicing in test-driven development pairs each behavior-driven test with minimal functional code using tracer bullets. This prevents the brittle, coupled test suites caused by writing all tests before implementation, ensuring tests verify public interfaces.

To write behavior-driven tests that survive refactoring, design deep modules with testable interfaces first. Verify user-facing behavior through iterative red-green-refactor cycles rather than testing internal implementation details to maintain a robust codebase.

Writing all tests before implementation, or horizontal slicing, leads to low-quality code because it creates brittle and coupled test suites. It contrasts with vertical slicing, which iteratively pairs behavior-driven tests with minimal functional code.

Yes, you can use the red-green-refactor cycle for new feature planning by executing vertical slices. This disciplined test-driven development workflow guides you to build minimal functional code paired with behavior-driven tests for user-facing behavior.

You should not use horizontal slicing when building new features that require maintainable, deep module design. It causes brittle, coupled test suites by verifying internal implementation details instead of public interfaces through iterative red-green-refactor cycles.