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 agentmods add rules/nerds-odd-e/doughnut/unit-testinggit clone --depth 1 https://github.com/nerds-odd-e/doughnutWhat 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 | $0.01343 | $0.01343 |
| Opus 5 | $0.00672 | $0.00672 |
| Sonnet 5 | $0.00269 | $0.00269 |
| Haiku 4.5 | $0.00134 | $0.00134 |
Grade A, and why
unit-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 2d 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 — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.
"Small test" style
This repo’s automated tests are E2E or unit tests — nothing in between. Write unit tests in the "small test" style below.
A "small test" means: a fast, in-process unit test (JUnit, Vitest, Bach, …) that drives a stable boundary with crafted data/makeMe, exercises real lower-level production code, and mocks only external dependencies. Stack commands, entry points, and tooling stay in the package rules (frontend.mdc / frontend-testing.mdc, backend.mdc / backend-testing.mdc, cli.mdc, mcp-server.mdc).
Stable boundary
- Drive the outermost (or domain-stable) interface. Prefer the public surface under test — e.g. a controller, mounted component, CLI
run/runInteractive, MCP tool — or an interface that is itself a deliberate, domain-stable contract (pure algorithm, validation API). Do not add a test class per internal production class, and do not widen exports only so tests can reach helpers. - Cover lower layers with data, not with more test surfaces. Craft realistic, scenario-specific preconditions and fixtures so one boundary test exercises the real lower-level production routines. Prefer that over isolating each collaborator behind mocks or thin wrapper tests.
- Build those fixtures with
makeMe— keep construction concise (see below). - Do not mock unless external or exceptional. Mock only true external dependencies (third-party APIs, network services, and the like) or extremely rare special cases. Package rules name the allowed exceptions (
OpenAIClient, frontendmockSdkServicefor the backend HTTP API, CLI spies ondonut-api, etc.). Prefer the real database, real in-process collaborators, and real browser rendering inside the system under test.
Focused assertions
- One behavior per test. Assert only what this scenario uniquely establishes.
- Canonical shape once. Shared post-conditions belong in one test. Sibling scenarios assert only their delta.
- Different precondition ≠ re-assert unrelated post-condition. If outcome X is clearly independent of what changed in the setup, do not repeat X.
- Prefer asserting the positive signal over “not the other message/alert” when the positive already distinguishes the case.
- In loops (thresholds, retries, frame polls), assert the loop result, not the same intermediate outcome every iteration.
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.
- 2d ago First seen · 83 lines · 1,343 tokens per session scan A aa1e23b7609f
unit-testing is a cursor rule published in the GitHub repository nerds-odd-e/doughnut (49 stars, last pushed 2d ago), licensed MIT. It adds 1,343 tokens to every session, about $0.0067 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 2026-08-30.
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