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Real file from a public repo · synced Sep 3, 2026

writing-unit-tests

Use when writing or refactoring unit tests - a new test file, added cases, a flaky test, an unreadable one. Encodes behavior-first testing: one behavior per test, names that state the claim, deterministic setup, mocks only at boundaries you do not own. Use whenever a test is being written, even a quick one, and whenever a test needs a sleep, a mock of your own code, or a copy of the implementation's math.

Works with

Claude CodeCursorCodex CLIGitHub CopilotGemini CLI

Install in three steps

  1. 1

    Download the ZIP

    One file per agent, plus INSTALL.md with the exact paths below.

  2. 2

    Claude Code: copy SKILL.md into your skills folder

    .claude/skills/writing-unit-tests/SKILL.md    # this project
    ~/.claude/skills/writing-unit-tests/SKILL.md   # every project
  3. 3

    Other agents: use the matching file

    skill.mdc goes in Cursor’s .cursor/rules/. AGENTS.md works as GitHub Copilot instructions, a legacy .cursorrules, or a Codex / Gemini CLI instructions file.

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