A testing workflow for adding tests to existing code. It finds untested behaviors, covers normal and failure cases, reproduces bugs with tests, and checks that the test suite and build pass.

Use it to backfill test coverage before a release, after a bug, or when an important code path has no tests.

It helps add missing protection to older or risky code and prevents known bugs from returning.

test-writer — Skill for Claude Code and Codex by oreum-ai/smartstack

Install

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.

Any agent

npx skills add oreum-ai/smartstack --skill test-writer

Clone the repo

git clone --depth 1 https://github.com/oreum-ai/smartstack

Made for: Claude Code, Codex.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/oreum-ai/smartstack/test-writer/github.svg)](https://agentmods.dev/skills/oreum-ai/smartstack/test-writer)

Your own site

<a href="https://agentmods.dev/skills/oreum-ai/smartstack/test-writer"><img src="https://agentmods.dev/badge/skills/oreum-ai/smartstack/test-writer/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/oreum-ai/smartstack/test-writer"><img src="https://agentmods.dev/badge/skills/oreum-ai/smartstack/test-writer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 316 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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	$0.00000	$0.00316
Opus 5.5	$0.00000	$0.00126
Sonnet 5.5	$0.00000	$0.00063
Haiku 4.5	$0.00000	$0.00032

Measured 2mo ago against content hash e1ff997c2eab, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

test-writer 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 2mo 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.

ai-rules/skills/test-writer/SKILL.md · 22 lines

What it actually says

Skill: Test Writer

When to use

To add tests to code that already exists (vs tdd, which writes tests first for new risky logic). Use it to backfill coverage before a release, after a bug, or when a risky path has no protection.

Procedure

Find the gaps. Read the target module; list its behaviors and branches. Mark which have no test. Prioritize risky ones (auth, money, domain logic, data integrity) per rules/testing.md.
Cover the contract. For each behavior write one happy-path test and one+ failure-path tests (invalid input, missing data, unauthorized, boundary values).
Pin any bug. If you're here because of a bug, first write a test that reproduces it (fails now), then confirm it passes after the fix. Prevents regressions.
Keep tests clean. One behavior per test; sentence-like names; deterministic; independent. Use fakes/mocks or a test database for data logic — never prod data.
Run and confirm. All green; none skipped/commented. Lint/build clean.
Record. Note new coverage in the session summary; if a bug was involved, log it in the ledger.

What to test vs skip

Test: logic with branches, calculations, state transitions, access control, error handling.
Skip/minimal: trivial getters, pure layout, generated code. Cover behavior, not pixels.

Changes

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.

2mo ago First seen · 22 lines · 0 tokens per session scan A e1ff997c2eab

Subscribe to this mod's changes

test-writer is a skill published in the GitHub repository oreum-ai/smartstack (6 stars, last pushed 5mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 316 tokens. 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.

Testing

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An uncompromising Academic Research Engineer. Operates with absolute scientific rigor, objective criticism, and zero flair. Focuses on theoretical correctness, formal verification, and optimal implementation across any required technology.

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test-writer