ada-test-driven-development

Write one minimal failing test for a single behavior, run it with pytest to confirm it fails for the expected reason, then write the simplest code to make it pass. After green, refactor while keeping all tests passing, and repeat one cycle at a time.

RED-GREEN-REFACTOR is the TDD loop: write a failing test (RED), write minimal code to make it pass (GREEN), then clean up the code while keeping tests green (REFACTOR). Each cycle covers one behavior before moving to the next.

Skip TDD for throwaway prototypes, generated code, configuration-only changes, and exploratory spikes where the design is still unknown. For exploration, use a spike approach first, then restart implementation with TDD once the design is clear.

A test that passes immediately proves nothing — it may test the wrong thing or existing behavior. Watching it fail confirms the test actually exercises the missing feature and will catch regressions later.

Delete the untested code and start over with a failing test. Keeping it as reference leads to adapting it during test writing, which is effectively testing after the fact and produces biased, low-confidence tests.