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 axiomantic/spellbook --skill testing-strategygit clone --depth 1 https://github.com/axiomantic/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/axiomantic/spellbook/testing-strategy)<a href="https://agentmods.dev/skills/axiomantic/spellbook/testing-strategy"><img src="https://agentmods.dev/badge/skills/axiomantic/spellbook/testing-strategy/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/axiomantic/spellbook/testing-strategy"><img src="https://agentmods.dev/badge/skills/axiomantic/spellbook/testing-strategy.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 | $0.00066 | $0.00778 |
| Opus 5.5 | $0.00026 | $0.00311 |
| Sonnet 5.5 | $0.00013 | $0.00156 |
| Haiku 4.5 | $0.00007 | $0.00078 |
Grade A, and why
testing-strategy 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 — 63 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Testing Strategy
Invariant Principles
- Scope Matches Change - Test selection mirrors the scope of the code change; a single-file change does not justify a full suite run.
- Marks Are Proactive - Tests are marked (slow, gpu, network) at authoring time based on what they require, not how fast they happen to run today.
- Full Suite Runs Once - The complete test suite runs once per work unit completion, not after every incremental change.
Test Tiers
| Tier | Time | What | When |
|---|---|---|---|
| Unit | <1s each | Pure logic, no I/O, no external deps | After every change |
| Integration | 1-5s each | Real resources (DB, filesystem, network) | After completing a logical unit of work |
| E2E / Slow | >5s each | Full pipelines, large data, real services | Once per feature branch, before PR |
Selecting What to Run
- Single file changed: Run only the test file(s) that directly test that module.
src/auth/login.pychanged? Runtests/test_login.py. - Shared dependency changed (types, config, utilities): Grep for imports of the changed module across test files. Run all direct consumers.
- Multi-file task complete: Run unit tests for all changed files in one command.
- All tasks in a work unit complete: Run the full suite once.
- If >5 test files affected: Run the full fast tier rather than listing individually.
Batching: Write code for task 1, run targeted tests, write code for task 2, run targeted tests, run full suite once at end.
Writing Tests for Speed
Mock expensive resources in unit tests. Use smallest possible inputs. Never sleep in tests. One assertion focus per test. No fixtures heavier than the test itself.
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 · 63 lines · 66 tokens per session scan A 60fb7fb18009
testing-strategy is a skill published in the GitHub repository axiomantic/spellbook (10 stars, last pushed 3d ago), licensed MIT. It adds 66 tokens to every session and 778 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 2026-09-03.
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