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What is TDD and when does it help?

Tags

#tdd#workflow#design

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Answer

TDD (Test-Driven Development) is writing a failing test first, then making it pass and refactoring. It helps clarify requirements and design when logic is complex or risky.

Advanced answer

Deep dive

TDD cycle:

Red: write a failing test.
Green: make it pass with minimal code.
Refactor: improve design without changing behavior.

It’s best for algorithms, business rules, or APIs with unclear requirements.

Examples

TDD for a parser:

Given "a,b", expect two tokens -> implement -> refactor

Common pitfalls

Writing tests after the fact but calling it TDD.
Over-specifying implementation details in tests.
Using TDD where rapid prototyping is more appropriate.

Interview follow-ups

How do you balance TDD with speed?
When do you skip TDD?
How does TDD affect refactoring confidence?

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