Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/aldianriski/lean-flow/tddnpx skills add aldianriski/lean-flow --skill tddgit clone --depth 1 https://github.com/aldianriski/lean-flowWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/aldianriski/lean-flow/tdd)<a href="https://agentmods.dev/skills/aldianriski/lean-flow/tdd"><img src="https://agentmods.dev/badge/skills/aldianriski/lean-flow/tdd.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00088 | $0.01293 |
| Opus 5 | $0.00044 | $0.00647 |
| Sonnet 5 | $0.00018 | $0.00259 |
| Haiku 4.5 | $0.00009 | $0.00129 |
Grade A, and why
tdd scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.
tdd
Behaviour-driven test-first development. Build in vertical slices: one test → one implementation → repeat. Each test responds to what the last cycle taught you.
For fixing a bug, use /diagnose (it writes the failing regression test before the fix). This skill
is for new behaviour.
Philosophy
Tests verify behaviour through public interfaces, not implementation details. Code can change entirely; the tests shouldn't.
- Good test — integration-style, exercises a real code path through the public API, reads like a spec ("user can checkout with a valid cart"). Survives refactors because it ignores internal shape.
- Bad test — coupled to implementation: mocks internal collaborators, tests private methods, or verifies through a side channel (querying the DB instead of the interface). The tell: it breaks when you rename an internal function but behaviour hasn't changed.
When a test is hard to write, or you're unsure what to mock / how to shape an interface for
testability → ${CLAUDE_SKILL_DIR}/references/testability.md (mock-at-boundaries · DI · good/bad
examples · refactor candidates). Unsure which kind of test (unit/integ/e2e/perf/load) fits the
task → ${CLAUDE_SKILL_DIR}/references/test-strategy.md. What makes a test good — the quality
checklist + the 70/20/10 pyramid + risk-tier→depth, as host-project guidance → ${CLAUDE_SKILL_DIR}/references/test-standard.md.
Anti-pattern: the tautological test
An assertion that recomputes the expected value the way the code does passes by construction and
can never disagree with the code — expect(add(a, b)).toBe(a + b), a snapshot derived by hand using
the same formula, a constant asserted equal to itself. It is green on day one and stays green through
the bug it was written to catch, so it reads as coverage while testing nothing.
The tell: ask what would have to be wrong for this to fail? If the only answer is "the language", it is tautological. Same family as L-058 — a check that can only pass is the failure it exists to prevent, and a test suite hides it better than a gate does.
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 5d ago First seen · 99 lines · 88 tokens per session scan A 9cc29b11aabb
tdd is a skill published in the GitHub repository aldianriski/lean-flow (5 stars, last pushed 6d ago), licensed MIT. It adds 88 tokens to every session and 1,293 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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Test-driven development. Use when the user wants to build features or fix bugs test-first, mentions "red-green-refactor", or wants integration tests.
strict-tdd
Strict RED->GREEN->REFACTOR test-driven development with enforcement. Never write production code before a failing test. Atomic commits per TDD cycle.
tdd
This skill should be used when the user wants to implement features or fix bugs using test-driven development. Enforces the RED-GREEN-REFACTOR cycle with vertical slicing, context isolation between test writing and implementation, human checkpoints, and auto-test feedback loops. Uses multi-agent orchestration with the…
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Execute tasks from a track's implementation plan following TDD workflow.