PickBits University — AI Test Validator

This is a Claude/Codex "skill": a folder with a SKILL.md that teaches your AI
assistant to run a specific workflow.

WHAT IT DOES
  Proves whether your AI-generated tests can actually fail. It runs mutation
  testing against an 80% mutation-score gate (mutmut for Python, Stryker for
  JavaScript, PITest for Java), greps your suite for the weak assertions AI
  loves to write, applies the 3-mutation recipe by hand to your most important
  function, and then renders a verdict on every test file:
  KEEP / FIX / DELETE-AND-REWRITE.

  The rule it enforces: a test is only valuable if it can fail. If it can't
  detect broken code, it's worse than no test at all.

  It also drops a real .github/workflows/test-quality.yml into your repo, so the
  80% gate holds on the next pull request too.

INSTALL
  Copy the vc-ai-test-validator.skill folder into your project's .claude/skills/
  directory (create it if it doesn't exist). Then just ask Claude to do the
  thing — e.g. "Claude wrote my tests, can I trust them?" or "my test suite is
  green but production broke — check if these tests actually test anything."

  No terminal? Ask your assistant: "Set up mutation testing for this project and
  run it against our test suite. Tell me the mutation score and which mutations
  survived."

WHAT'S IN THE FOLDER
  SKILL.md                              the workflow itself
  references/validation-patterns.md     the 4 validation patterns + 3 bad-test
                                        patterns, with all the code
  references/red-flags.md               the 6 red flags, the 6-step checklist,
                                        the Nuclear Option delete thresholds
  references/useless-test-exemplars.md  the 3 tests that can never fail
  scripts/test-quality.yml              drop-in CI gate: 80% mutation score
  scripts/assertion-strength-check.sh   the two weak-assertion greps, runnable

RELATED SKILLS
  This is step 3 of a 3-skill loop:
    vc-ai-first-tdd-planner  -> plan the tests
    vc-test-prompt-builder   -> prompt the AI for them
    vc-ai-test-validator     -> this one; the merge gate

A NOTE ON OPENING SKILL.md
  On Windows, double-clicking SKILL.md opens Notepad, which may show a blank
  page — its Markdown view doesn't understand the settings block at the top of
  the file. The file is fine. Open it in VS Code, or choose "Open in Syntax
  View" in Notepad. You don't need to read it to use it.

Source lesson: https://pickbits.ai/university/vibe-coder/06-tdd-with-ai/validating-ai-tests
