tdd-workflow

Test-Driven Development (TDD) starts with writing a failing test before implementation. Write your test for a specific game mechanic—like Tetris rotation—then write minimal code to pass it, and refactor while keeping tests green. This workflow ensures your logic is testable and correct from the start.

Yes. fast-check enables property-based testing in TypeScript projects. With Bun's test runner, you can define properties that generate random test cases, verifying game logic holds across many inputs. This catches edge cases that manual tests might miss.

Co-located tests place test files next to implementation files in the same directory. This keeps related logic visible together, makes refactoring easier, and clarifies coverage. For a Tetris game, store rotation tests beside rotation.ts for clarity and maintainability.

Enforce coverage targets by writing tests before code (red-green-refactor cycle), using property-based testing to explore edge cases, and measuring coverage with Bun's test tools. Co-located tests make uncovered paths visible, helping you reach and maintain 100% coverage for critical mechanics.

Result<T,E> patterns (success or error returns) make failure modes explicit in game logic. Instead of throwing exceptions, return Results for operations like rotation or placement. This approach integrates cleanly with TDD, improves testability, and reduces surprises in production code.

TDD writes tests first, driving design through test requirements; post-hoc testing adds tests to existing code. TDD catches design issues early, ensures testability by default, and creates living documentation. For game logic, TDD prevents bugs in rotation, placement, and scoring before they ship.