How Test-Driven Development Eliminates the Guesswork From Writing Code

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A software developer shares how repeated debugging struggles in legacy codebases led them to adopt Test-Driven Development (TDD), a practice where failing tests are written before any production code. The TDD cycle follows three steps: writing a failing test (Red), writing just enough code to pass it (Green), and then refactoring safely (Refactor). This approach provides immediate feedback, encourages cleaner function design, and creates living documentation of intended behavior. The developer illustrates the risk of skipping TDD with a discount-eligibility function where an untested leap-year edge case for VIP users slipped into production. The experience highlights how writing tests after the fact often means critical business rules are never questioned or verified upfront.

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ProgrammingDEV Community ·

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