test-optimization

A workflow for finding and speeding up the slowest tests in a test suite. It applies to unit tests and Cypress end-to-end tests across different kinds of projects.

In plain words
What is it for?
Use it to identify the slowest tests, optimize them in grouped slices, address flaky behavior, and compare performance again afterward.
Why use it?
It replaces guesswork with profiling, removes redundant tests and fixed waits, and checks that changed tests remain stable.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/nerds-odd-e/doughnut/test-optimization
Any agent
npx skills add nerds-odd-e/doughnut --skill test-optimization
Clone the repo
git clone --depth 1 https://github.com/nerds-odd-e/doughnut

Made for: Claude Code, Codex.

Per session 121 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,129 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00121 $0.04129
Opus 5 $0.00060 $0.02065
Sonnet 5 $0.00024 $0.00826
Haiku 4.5 $0.00012 $0.00413

Measured 2d ago against content hash 3424f677ba6e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

test-optimization 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.

.agents/skills/test-optimization/SKILL.md · 351 lines

How it starts

The opening of the file, as written. The whole thing — 351 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose: Systematic test-performance workflow for any sub-project (backend, frontend, cli, mcp-server, E2E).

Output: Optimized tests with per-slice commits + summary ending with ## TEST OPTIMIZATION COMPLETE.

When --resolve is given, skip every other step and go straight to resolve_candidates.

Git does not use the Nix prefix. All other repo tooling does: CURSOR_DEV=true nix develop -c …

Non-negotiable rules (every optimization pass):

  1. Remove or simplify redundant tests first — merge overlapping scenarios, drop duplicate setup, delete tests that only repeat coverage elsewhere.
  2. No fixed-time waits — no sleep, no cy.wait(ms) without an assertion, no arbitrary setTimeout / debounce-timeout polling in unit tests. Use assertions, intercept aliases, fake timers, or API/testability setup.
  3. Flaky is failure — re-run touched tests until stable; fix root cause, do not mask with retries.

Execution model: After writing the plan, always use execute-plan (.agents/skills/execute-plan/SKILL.md). Coordinator delegates each group to a fresh sub-agent; each slice runs post-change-refactor, then commits and pushes. Do not accumulate context across slices in one agent.

E2E skip tag: @skipOptimizationDueToKnownNecessarySlowness on a Scenario or Feature marks known-necessary slowness. Profile runs exclude it via --expose tags=… (see profile). Adding the tag is a developer decision (Jidoka) — propose only; do not add it yourself.

Candidates: .planning/test-optimization-blacklist.md holds Candidates from optimization runs (proposals only). Keep that section; do not invent a Skip list there.

Do not commit raw profile JSON (large, machine-specific). Gitignored paths: e2e_test/reports/, .planning/*-profile-results.json, .planning/quick/*-profile-results.json, ongoing/*-profile-results.json.

Goal: for each Candidate, decide whether the slow test earns its cost, or whether a cheaper test gives the same protection.

For each Candidate:

  1. Read the actual test (feature/scenario or unit test) plus the sibling scenarios in the same file and any backend/frontend unit tests the blacklist note references. Confirm what unique behavior it actually protects.
  2. Weigh the slow test against alternatives. Ask whether one or more unit tests (or a mocked E2E scenario) could give the same coverage, behavioral protection, and external user-value clarity. Remember: unit tests usually cannot reproduce the external user-value clarity of a genuine multi-step UI/PTY journey — so inherent-cost journeys stay as E2E.
  3. Distinguish inherent vs avoidable slowness. Cost from genuine product behavior (full page load, PDF/canvas render, PTY/Ink startup, frontend session state not replicable via API) is inherent. Cost from a live network call, redundant setup, or coverage duplicated elsewhere is avoidable — do not label avoidable cost as "necessary".

Resolve each Candidate with exactly one of:

Read the full file on GitHub · 351 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

  1. 2d ago First seen · 351 lines · 121 tokens per session scan A 3424f677ba6e

Subscribe to this mod's changes

test-optimization is a skill published in the GitHub repository nerds-odd-e/doughnut (49 stars, last pushed 2d ago), licensed MIT. It adds 121 tokens to every session and 4,129 once invoked, about $0.0006 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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