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 kid-sid/codex-spellbook --skill testinggit clone --depth 1 https://github.com/kid-sid/codex-spellbookWrote 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/kid-sid/codex-spellbook/testing)<a href="https://agentmods.dev/skills/kid-sid/codex-spellbook/testing"><img src="https://agentmods.dev/badge/skills/kid-sid/codex-spellbook/testing/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/kid-sid/codex-spellbook/testing"><img src="https://agentmods.dev/badge/skills/kid-sid/codex-spellbook/testing.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 | $0.00043 | $0.00751 |
| Opus 5 | $0.00022 | $0.00376 |
| Sonnet 5 | $0.00009 | $0.00150 |
| Haiku 4.5 | $0.00004 | $0.00075 |
Grade A, and why
testing 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 — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Testing
Write tests that isolate behavior, document intent, and fail for one reason at a time.
When to Activate
- Add tests for new behavior
- Refactor a flaky or slow test suite
- Decide whether a collaborator should be mocked
- Raise or enforce coverage expectations
- Convert duplicated tests into parameterized cases
- Review a PR for missing test coverage
- Drive a change with TDD
Test Structure
| Phase | Purpose | Rule |
|---|---|---|
| Arrange | Build inputs and collaborators | Keep setup minimal and explicit |
| Act | Execute one behavior | One action per test |
| Assert | Verify outcome | Assert observable effects, not internals |
Naming and Coverage
| Style | Example |
|---|---|
| Python | test_create_user_rejects_duplicate_email |
| TypeScript | it("rejects duplicate email on createUser") |
| Go | func TestCreateUser_RejectsDuplicateEmail(t *testing.T) |
| Codebase Type | Target |
|---|---|
| Shared library | >= 90% line coverage |
| Backend service | >= 80% line coverage with integration coverage on critical flows |
| Frontend app | >= 70% on logic-heavy modules, plus E2E coverage on core journeys |
Mock vs Real
| Dependency | Default | Reason |
|---|---|---|
| Database adapter in unit tests | Mock or in-memory fake | Keep units fast |
| Pure domain services | Real | No need to mock deterministic logic |
| HTTP clients | Mock at network boundary | Avoid external flake |
| Serialization and validation | Real | Contract drift matters |
TDD and Parameterization
| Step | Goal |
|---|---|
| Red | Prove the behavior is missing |
| Green | Implement the smallest passing change |
| Refactor | Improve structure without changing behavior |
Python
@pytest.mark.parametrize(("input", "expected"), [("A", "a"), ("B", "b")])
def test_normalize_code(input: str, expected: str) -> None:
assert normalize_code(input) == expected
TypeScript
it.each([
["A", "a"],
["B", "b"],
])("normalizes %s", (input, expected) => {
expect(normalizeCode(input)).toBe(expected);
});
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 · 114 lines · 43 tokens per session scan A 8035f280fc33
testing is a skill published in the GitHub repository kid-sid/codex-spellbook (21 stars, last pushed 4mo ago), licensed MIT. It adds 43 tokens to every session and 751 once invoked, about $0.0002 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 2026-09-03.
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