Daily iOS
Testing

TDD on an existing project

This one comes up onsite: "how does your team use tests today, and how would you follow TDD on a real project?" Answer it around a realistic way to bring TDD into an existing app that already has a lot of code.

How would an interviewer hear this answer? You'll see whether they'd move on, dig in, or say no, and which sentences would trip you up. Your score doesn't change.
See the short answer

On an existing app, start test-first with bug fixes and new logic instead of a full TDD rollout. Write the failing test that reproduces each bug report first, and hold Red-Green-Refactor for new features at the view model or use case level so the team feels the benefit early.

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