Use this skill to turn a non-deterministic test into a deterministic one by finding why it sometimes fails, not by retrying it until it passes. The recurring failure mode it prevents is "fix" by sleep increase, retry annotation, or disabling — all of which hide the defect (which is sometimes in the code, not the test) and erode trust in the suite.
Flaky Test Diagnosis is a community-contributed Claude Code skill in the testing sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/flaky-test-diagnosis/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when: a test passes and fails non-deterministically (flaky), fails only under load/parallelism/sanitizers, fails in CI but not locally, or fails depending on run order - diagnosing timing races, order dependence, shared global state, unseeded RNG, real-clock/timezone/locale reliance, real network/filesystem dependence, and hash/iteration-order assumptions, then making it deterministic.
The Flaky Test Diagnosis Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 153,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
mkdir -p ~/.claude/skills/flaky-test-diagnosis curl -L https://claudskills.com/skills/flaky-test-diagnosis/SKILL.md \ -o ~/.claude/skills/flaky-test-diagnosis/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/flaky-test-diagnosis/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/flaky-test-diagnosis/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\flaky-test-diagnosis\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.
For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.
SKILL.md from the source repository to ~/.claude/skills/flaky-test-diagnosis/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Flaky Test Diagnosis is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.If you reference this skill in a blog post, paper, or documentation, you can cite it as:
@misc{flaky-test-diagnosis-2026,
author = {sjinks},
title = {Flaky Test Diagnosis [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/flaky-test-diagnosis/}
}Grade A · scanned 2026-07-18 — free static scan against the OWASP Agentic Skills Top 10.
No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›
Browse all Engineering skills in the ClaudSkills registry, or explore these other picks from the same category:
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SKILL.md files, not affiliated with, endorsed by, or sponsored by Anthropic.