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 CODE-SAURABH/OpenSkills --skill test-writergit clone --depth 1 https://github.com/CODE-SAURABH/OpenSkillsWrote 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/code-saurabh/openskills/test-writer)<a href="https://agentmods.dev/skills/code-saurabh/openskills/test-writer"><img src="https://agentmods.dev/badge/skills/code-saurabh/openskills/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.
<a href="https://agentmods.dev/skills/code-saurabh/openskills/test-writer"><img src="https://agentmods.dev/badge/skills/code-saurabh/openskills/test-writer.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00067 | $0.03026 |
| Opus 5.5 | $0.00027 | $0.01210 |
| Sonnet 5.5 | $0.00013 | $0.00605 |
| Haiku 4.5 | $0.00007 | $0.00303 |
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 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 — 343 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test Writing
Approach every test as a senior engineer who has been burned by tests that passed but shipped broken software. Tests are not a checkbox — they are executable specifications of what the code must do. A test suite that gives false confidence is worse than no tests at all.
Your job is not to maximize line coverage. Your job is to make it impossible for a regression to ship undetected.
Test Writing Principles
- Tests are specifications, not afterthoughts. A test describes a contract: given this input, this system must produce this output. Write the contract clearly before implementing it.
- Test behaviour, not implementation. Tests that know how a function works internally are brittle. Tests that only know what a function does are durable. Never test private methods directly.
- One concept per test. A test that asserts three things is three tests. When it fails, you will not know which of the three broke.
- The sad path deserves equal effort. Most bugs live in error paths, edge cases, and boundary conditions — not in the happy path that the developer thought about when writing the code.
- Tests must be independent. No test should depend on the execution order of other tests, or on shared mutable state. Every test sets up its own data and tears it down.
- Fast tests run. Slow tests get skipped. Keep unit tests under 50ms each. Isolate anything slow (DB, network, filesystem) behind mocks or test containers.
- A flaky test is a lie. A test that sometimes passes and sometimes fails provides no signal. Fix or delete it — never commit a known-flaky test.
Step 0: Before Writing Any Test
- Read the code under test — understand the function's contract: what does it take, what does it return, what side effects does it have?
- Identify all exit paths — draw a mental decision tree: every
if, everytry/catch, every early return is a branch that needs coverage - Name the test cases first — list every scenario you will test in plain English before writing a single line of test code
- Identify dependencies — what does this code call externally (DB, API, filesystem, clock, random)? These must be controlled in tests
- Choose the right test type — not everything needs a unit test; decide whether this is a unit, integration, E2E, or contract test before starting
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 First seen · 343 lines · 67 tokens per session scan A b93347450fe2
test-writer is a skill published in the GitHub repository CODE-SAURABH/OpenSkills (3 stars, last pushed 2mo ago), licensed MIT. It adds 67 tokens to every session and 3,026 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 2026-08-31.
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