validation-first-approach

Test-driven development (TDD) follows the Red-Green-Refactor cycle: write a failing test first, implement minimal code to pass it, verify success, then refactor. This ensures tests verify intended behavior and prevent regressions.

Start writing tests before implementation by creating a failing test that defines the desired feature behavior. Verify the test fails for the right reason, then write the minimum code required to make it pass.

If a test passes before implementation, it indicates a testing anti-pattern or a flawed assertion. The TDD workflow requires verifying test failures first to guarantee the test actually validates the intended software behavior.

Yes, TDD supports refactoring existing software by ensuring a strong foundation of automated tests. After achieving a passing test, you refactor the code while verifying the test still succeeds, preventing new regressions.

The best way to prevent testing anti-patterns is enforcing strict TDD principles. This approach identifies and discourages practices that undermine testing effectiveness, addressing common rationalizations to ensure code quality and reliability.

You should reconsider a test-first approach when dealing with purely exploratory or throwaway code. Strict TDD enforces automated tests to guide development, which may slow down rapid prototyping where long-term code quality is not a concern.