stevennitesh Test-driven development
Deliver one settled observable behavior through:
RED -> GREEN -> REFACTOR
No observed behavioral RED, no TDD. After-the-fact proof can still be useful, but it cannot replace RED evidence or justify a TDD claim.
Admit only under the description's explicit user or repository-policy trigger. Ordinary implementation may add or change tests without invoking TDD. The caller retains scope and later delivery; this skill owns the inner loop.
Read Test shape only when the useful test boundary or independent expected result remains unclear after inspecting nearby tests. Read Test doubles before adding a test-specific substitute.
RED
Choose one accepted observable behavior, the highest useful stable interface that exposes it, an independently derived expected result, and the focused test command. Before writing the test, name the realistic production break it should catch. If the behavior, oracle, authority, or a safe red-capable check is unavailable, stop before production mutation and report that material gap.
Reuse or extend the narrowest existing behavior test or case table that can express the behavior. If none reaches it, create the smallest repo-native check whose signal justifies its cost. Do not add a dependency, service, public test hook, broad fixture, or brittle mock merely to satisfy TDD. An honest gap is better than a bad test.
Run the focused test. Continue only when it fails because the accepted behavior is missing or wrong, not because setup, imports, fixtures, typos, environment, or unrelated code failed. An immediate pass is not RED. If a trustworthy RED cannot be observed safely, do not claim TDD or delete pre-existing work to recreate the ritual.
GREEN
Make the smallest acceptance-complete implementation change that makes the focused test pass. Change a correct assertion only when its accepted behavior, oracle, or chosen interface was wrong.
Run the focused test and the nearest checks justified by repository policy, shared impact, or concrete risk. Keep unrelated baseline failures separate.
REFACTOR
Remove slice-local duplication or awkwardness while the behavior stays green. New behavior or a public-contract change starts another RED.
Complete when the selected behavior crossed observed RED before its implementation and remains green under the relevant proof. Return concise prose naming the observed RED, final GREEN and nearby proof, and any material gap.