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Verify Python Change Tests

Checks that Python changes are caught by tests by running mutants and adding tests until they fail.

Source Download skill
Repository
sickn33/agentic-awesome-skills
Stars
49,023
Licence
MIT
Files
1 file

What it does

When Claude writes or changes Python code, this skill makes it prove the change is tested. It runs a mutation checker that deliberately breaks the changed lines in small ways and confirms the tests catch each break, adding or strengthening tests until they do. The user gets a report of evidence (which checks passed, which mutants were caught, which new tests fail on the old code) rather than having to read the diff.

Great for

  • Python developers using pytest who want proof that new code is actually tested
  • Teams reviewing AI-written Python changes before merging
  • Anyone who wants a verdict on test coverage quality, not just a pass/fail on existing tests

Skip it if

  • Non-Python projects, since it targets Python and pytest (wrong tool for other languages)
  • Reviewing a whole test suite; the skill's own docs point to a different skill (agentic-test-audit) for that
  • Situations needing guaranteed bug-free code: the skill states a runner verdict cannot prove every defect would be caught

Try asking

  • “Check whether the change I just made is covered by tests before we call it done”
  • “Run verify on my uncommitted work and tell me which mutants survived”
  • “Compare my branch against main and show which new tests fail on the old code”
  • “Write tests for the edge cases in this function until the mutation check passes”
Step-by-step guide: how to use Verify Python Change TestsInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 1 original files, the MIT licence and an attribution note.

    agentic-verify.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip agentic-verify.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip agentic-verify.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Pass the project root (where pytest runs), not a sub-folder or single file, or the check will not work correctly.
  • Give the verifier a clear success criterion first; the skill asks for one before coding and tests come out stronger.
  • Use a larger --budget-minutes for big changes, otherwise the result may be incomplete.

What's inside

  • SKILL.md

Redistributed unmodified from sickn33/agentic-awesome-skills under the MIT licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.