tdd-approach

Test-driven development prevents regressions by enforcing a red-green-refactor cycle: write a failing test specifying behavior, implement minimal code to pass, then refactor while tests stay green.

To write failing tests before implementation, create a runnable test case in your project's testing framework that describes the expected behavior, run it to confirm failure, then write the minimal code to make it pass.

Test-driven development is framework-agnostic and adapts to existing test infrastructures including pytest, Jest, and Go testing, requiring only a runnable test suite to execute iterative red-green-refactor cycles.

The best way to fix bugs using red-green-refactor cycles is to first write a failing test reproducing the bug, then implement the minimal code fix to make the test pass, preventing future regressions.

TDD workflows improve untested legacy code by adding incremental, test-backed changes, building confidence through specifying and verifying behavior with runnable tests before modifying the implementation.

Writing a failing test before implementation ensures behavior is explicitly specified and verified, preventing untested code paths and regressions by confirming the test fails for the right reason before code is written.