tdd-workflow

Test-driven development prevents regressions by codifying a disciplined red-green-refactor cycle to ensure new behaviour is specified by tests before production code is written. This reduces bugs and design drift across feature development and complex business logic.

The best way to structure unit tests for complex business logic is by prioritizing near-100% coverage for domain logic while mocking external ports. This focuses testing on behaviour rather than implementation, ensuring executable tests validate requirements accurately.

To apply the red-green-refactor cycle when fixing bugs, reproduce the bug with a failing regression test, implement the minimal code to make it pass, and then refactor while keeping tests green. Emphasize small 2–10 minute cycles to keep feedback fast.

Test-driven development requires integration tests for external adapters to verify interactions with external ports. While domain logic achieves near-100% unit test coverage with mocked ports, adapter integration tests ensure the complete system functions correctly.

Your test-driven development cycle feels slow because cycles are too large. Emphasize small 2–10 minute cycles to keep feedback fast and development focused, writing a single failing test for the next behaviour, implementing minimal code, and refactoring with tests green.

You can use TDD to specify complex business logic through executable tests by writing failing tests that describe the next behaviour and validating requirements before implementation. This iteratively drives out domain logic while maintaining high test coverage.