fix-flaky-test

fix-flaky-test is a skill for Claude Code, Codex from tmj-90/gaffer. It costs 69 tokens per session (498 once invoked), scanned A, original, Apache-2.0.

A workflow for diagnosing tests that sometimes pass and sometimes fail. Such tests are called flaky tests because their result changes without a relevant code change.

In plain words
What is it for?
Use it to reproduce an intermittent test failure, identify its source, fix the cause, and confirm the test and full suite remain stable.
Why use it?
It targets the underlying cause, such as timing, shared state, randomness, clocks, or external services, instead of hiding the problem with retries or longer waits.

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/tmj-90/gaffer/fix-flaky-test
Any agent
npx skills add tmj-90/gaffer --skill fix-flaky-test
Clone the repo
git clone --depth 1 https://github.com/tmj-90/gaffer

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for fix-flaky-test

README.md
[![agentmods](https://agentmods.dev/badge/skills/tmj-90/gaffer/fix-flaky-test.svg)](https://agentmods.dev/skills/tmj-90/gaffer/fix-flaky-test)
Your own site
<a href="https://agentmods.dev/skills/tmj-90/gaffer/fix-flaky-test"><img src="https://agentmods.dev/badge/skills/tmj-90/gaffer/fix-flaky-test.svg" alt="Measured on agentmods" height="20"></a>
Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 498 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 $0.00069 $0.00498
Opus 5 $0.00034 $0.00249
Sonnet 5 $0.00014 $0.00100
Haiku 4.5 $0.00007 $0.00050

Measured 4d ago against content hash 232d854c28a4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fix-flaky-test 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 4d 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.

runner/skills/fix-flaky-test/SKILL.md · 38 lines

What it actually says

Fix a flaky test

A flaky test fails non-deterministically. The job is to find the source of non-determinism and remove it — not to retry until it passes.

Steps

  1. Reproduce the flakiness. Run the named test repeatedly (a loop, or the runner's repeat flag) and, where relevant, in randomised order. Capture a failing run; you can't fix what you can't observe.
  2. Locate the non-determinism. It's almost always one of: timing (sleeps, races, unawaited async), test order / shared mutable state (leaked globals, DB rows, singletons), unseeded randomness, real clock/timezone, or network/external calls. Read the failure to narrow which.
  3. Fix the root cause. Await async properly and wait on conditions not timeouts; isolate state with proper setup/teardown; seed randomness and fake the clock; stub the external boundary. Do not add a retry, increase a sleep, or mark the test skipped — those hide the bug.
  4. Prove stability. Re-run the test many times (and in random order) and confirm it passes every time. Then run the full suite (run-tests) to confirm no regression.
  5. Evidence: the repeated-run command and a clean streak, plus the fix summary. Then use the record-evidence skill to record test_output against the AC and submit for review.

Rules

  • Fix the cause (timing/order/shared state/randomness), never add a retry or longer sleep.
  • Never skip or delete the test to make the suite green.
  • Demonstrate stability with many repeated passes, not a single run.
  • If the flake reveals a real product bug, note it; fix only what the ticket scopes.
  • Run on a branch (the create-branch skill), never a protected branch.
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. 4d ago First seen · 38 lines · 69 tokens per session scan A 232d854c28a4

Subscribe to this mod's changes

fix-flaky-test is a skill published in the GitHub repository tmj-90/gaffer (2 stars, last pushed 4d ago), licensed Apache-2.0. It adds 69 tokens to every session and 498 once invoked, about $0.0003 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 2026-08-31.