Tdd executor

Skill willianbs/skills/tdd-executor

Runs red/green/refactor loops against acceptance criteria and TEST_STRATEGY. Use when practicing TDD or when tests should lead implementation. Emits TDD_SESSION. Never skips red, never refactors on red, never claims green without command evidence.From its SKILL.md

Install

npx -y skills add willianbs/skills --skill tdd-executor

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SKILL.md

2.8 KB, 596 tokens by cl100k_base, as published. Nobody here has run it

Purpose

Implement behavior test-first with a disciplined red → green → refactor loop tied to AC IDs.

When to Use / When NOT to Use

Use when: user asks for TDD; high-correctness units; pairing with TEST_STRATEGY; implementing pure logic/API contracts.

Do not use when: spike/prototype explicitly throwaway; pure docs; exploratory defect triage (defect-analyst first).

Preconditions

At least one testable AC or behavior statement. Prefer TEST_STRATEGY + TASK_GRAPH. Project test command discoverable.

Inputs / Outputs

Inputs: AC IDs, TEST_STRATEGY, CONTEXT_PACK, task scope.

Outputs: TDD_SESSION (+ code/tests); may produce/update IMPL_REPORT fields.

Upstream / Downstream

Upstream: test-strategy-designer, delivery-planner, spec-validator.

Downstream: feature-implementer (if continuing), code-reviewer, quality-gate.

Core Principles

Red before implementation for the vertical under test.
Green: minimal code to pass.
Refactor only on green; keep tests green.
One failing behavior at a time.
Behavior-focused tests; avoid testing privates unless necessary.
Record exact commands and outcomes.
Stop if AC is untestable — hand back to spec-validator.

Process

For each AC/slice:

Red — write failing test; run; capture failure.
Green — minimal implementation; run; capture pass.
Refactor — clean structure; run; stay green.
Update TDD_SESSION log per cycle.
After cycles, summarize coverage vs AC IDs; note gaps.

Lite

Single function/bugfix: one red/green cycle + optional refactor.

Evidence Requirements

commands_run with fail then pass. No “should pass” without running.

Stop Conditions / Failure Modes

Condition	Action
Cannot get a failing test (already green)	Revisit AC / test design
Untestable AC	Hand off spec-validator
Refactor breaks tests	Fix before continuing

Severity + Confidence

N/A primarily; residual risk if ACs unverified.

Output Contract

## TDD_SESSION
AC focus: ...
Cycles:
  - red: command/result
  - green: command/result
  - refactor: command/result
Remaining gaps: ...
Decision: Proceed | ProceedWithConditions | Revise | Block

Handoffs

feature-implementer (broader wiring), code-reviewer, spec-validator, test-strategy-designer.

Never

Never write implementation before a failing test in TDD mode (unless user aborts TDD).
Never refactor on red.
Never invent green test results.

What ships with it: 1 file

769 B alongside SKILL.md

README.md769 B

Gives 3 of the 12 instructions most tdd skills give in 596 tokens

Counted across 439 of the 443 authors here whose files we hold, read 2026-08-07

Write minimal code to pass the testhere, and in 304 of 439, across 222 files
Write a failing test firsthere, and in 174 of 439, across 111 files
Refactor code only after tests passhere, and in 172 of 439, across 102 files
Watch the test fail before writing codein 145 of 439, across 97 files
Test one behavior per testin 108 of 439, across 46 files
Refactor code while keeping tests greenin 100 of 439, across 88 files
Delete code written before testsin 99 of 439, across 55 files
Run tests after each refactor stepin 88 of 439, across 57 files
Confirm the test fails for the right reasonin 66 of 439, across 62 files
Use real code instead of mocks unless unavoidablein 60 of 439, across 17 files
Reproduce bugs with a test before fixingin 53 of 439, across 36 files
Write tests before implementationin 51 of 439, across 43 files

Said here and by no other author read

record exact commands and outcomes
update the session log per cycle
summarize coverage versus acceptance criteria
stop if acceptance criteria is untestable
emit the session log

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.