# Test Changes

> Run and update Julia tests after changing test files. Use when adding to or modifying any test file under test/ or stdlib/**/test/.

- Skill: `julialang/test-changes` (Agent Skill)
- Install (CLI): `npx skillmds@latest add julialang/test-changes`
- Raw SKILL.md: https://api.skillmd.com/api/skills/julialang/test-changes/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: julialang (https://skillmd.com/u/julialang)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/julialang/test-changes

---


# Julia test changes

Use this when you change or add a Julia test.

- If you have changed a test (e.g. `foo`), run `make test-revise-foo` for the
  corresponding test to ensure that the test is still passing with your changes.
- If you are adding a new test, add it to an existing test file. Do not create a
  new test file unless explicitly instructed.
- Write one comment at the top of the test to explain what is being tested.
  Otherwise keep comments minimal.
- Use the environment variable `JULIA_TEST_FAILFAST=1` to make tests fail fast.
- Do not coordinate with fixed `sleep`s — loaded CI machines break any fixed
  delay. Synchronize on observable state (readiness markers, round-trips), or
  retry.