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 skills add clubpay/ronykit --skill writing-testsgit clone --depth 1 https://github.com/clubpay/ronykitWrote 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/clubpay/ronykit/writing-tests)<a href="https://agentmods.dev/skills/clubpay/ronykit/writing-tests"><img src="https://agentmods.dev/badge/skills/clubpay/ronykit/writing-tests/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/clubpay/ronykit/writing-tests"><img src="https://agentmods.dev/badge/skills/clubpay/ronykit/writing-tests.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00084 | $0.00671 |
| Opus 5.5 | $0.00034 | $0.00268 |
| Sonnet 5.5 | $0.00017 | $0.00134 |
| Haiku 4.5 | $0.00008 | $0.00067 |
Grade A, and why
writing-tests 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 1mo 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 — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing Tests
Test behavior, not implementation. A good test fails only when the contract breaks, and tells you exactly what broke.
When to use
- Before/while writing new behavior (TDD), or backfilling tests for legacy code
(pin current behavior with characterization tests first; for Go, see
go-design). - Deciding what deserves a test and at which level.
- A bug was found — write the failing test first, then fix it.
The test pyramid
- Unit (most): pure logic, fast, no I/O. Milliseconds.
- Integration (some): real boundaries — DB, queue, HTTP — wired together.
- End-to-end (few): full system through the public interface.
Push assertions down to the cheapest level that still proves the behavior.
TDD loop
- Red — write the smallest failing test for the next behavior.
- Green — write the least code to pass it.
- Refactor — clean up with tests green.
Commit at green. Never refactor and change behavior in the same step.
What makes a test valuable
- Tests behavior, not internals. Assert on observable outputs and effects, not private fields or call counts (avoid over-mocking).
- One reason to fail. Each test pins one behavior; the name says which.
- Deterministic. No reliance on time, ordering, network, or shared state.
- Readable. A reviewer understands the contract from the test alone.
- Fast. Slow suites get skipped; isolate slow tests behind tags/build flags.
Coverage
Coverage finds untested code; it does not prove correctness. Chase missing branches and error paths, not a percentage. A line covered without an assertion is not tested.
Anti-patterns
- Tautological tests — they restate the implementation instead of pinning
behavior: asserting a mock returns what you configured, re-deriving the
expected value with the same expression the code uses,
expect(X).toBe(X), or approving a snapshot nobody read. Use hand-computed expected values; delete tautological tests rather than fixing them. - Asserting implementation details that change during refactors.
- Tests that pass when the feature is broken (no real assertion).
- Mocking the thing under test, or mocking value objects.
- Shared mutable fixtures that couple unrelated tests.
- Snapshot tests so large nobody reviews the diff.
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.
- 1mo ago Changed · +9 lines · +37 tokens per session c5ad3cabb4ea
- 2mo ago First seen · 65 lines · 47 tokens per session scan A 4c2b8198d2d0
writing-tests is a skill published in the GitHub repository clubpay/ronykit (38 stars, last pushed 3d ago), licensed BSD-3-Clause. It adds 84 tokens to every session and 671 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-08-30.
Other skills, from other repositories
config-loader-helper
Diagnose configuration-related failures, enumerate required env vars, and guide safe local test setup (no secrets).
db-infra-mocks
Propose minimal seams and local substitutes so tests run without real RDBMS/Redis/Mongo infrastructure.
ci-orchestrator
Run a CI-like pipeline locally (format, lint, vet, static-analysis, tests) and summarize per-step results with remediation guidance.
fix-suggester
Diagnose failures and propose minimal, test-backed fixes with verification and rollback instructions.
qa-orchestrator
Orchestrate multi-step change workflows (search, analyze, propose, implement, verify) with explicit evidence and gate checks.
test-runner
Run and triage Go tests with correct environment handling; produce compact, actionable failure summaries.