When a test needs a stand-in for a collaborator (a database, clock, queue, HTTP client), reach for a fake before a mock in almost every case. A fake tests what the code does (observable state and behavior); an interaction mock tests how the code does it (the exact calls made) — and "how" is the part you most want to be free to change. This complements [[test-design]] (which covers test structure, and deliberately defers fakes-vs-mocks here) and pairs with [[sim-zero-mode]] for deterministic test environments.
Prefer Fakes Over Mocks is a community-contributed Claude Code skill in the general-misc sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/prefer-fakes-over-mocks/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when choosing or reviewing test doubles — deciding between a fake, stub, or mock for a collaborator. Default to fakes (working in-memory implementations); reserve interaction mocks for the narrow cases where the interaction itself is the contract.
The Prefer Fakes Over Mocks Claude Code skill is built for Claude Code users and developers across all disciplines looking for general-purpose AI assistance. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 196,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
mkdir -p ~/.claude/skills/prefer-fakes-over-mocks curl -L https://claudskills.com/skills/prefer-fakes-over-mocks/SKILL.md \ -o ~/.claude/skills/prefer-fakes-over-mocks/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/prefer-fakes-over-mocks/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/prefer-fakes-over-mocks/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\prefer-fakes-over-mocks\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/prefer-fakes-over-mocks/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. Prefer Fakes Over Mocks is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the General 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{prefer-fakes-over-mocks-2026,
author = {selamy-labs},
title = {Prefer Fakes Over Mocks [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/prefer-fakes-over-mocks/}
}Grade A · scanned 2026-09-28 — 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 General 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.