| name | write-tests |
| description | Write or revise Marin tests with an emphasis on behavior, regression coverage, pytest style, and avoiding "slop tests." Use when adding tests, fixing failing tests, reviewing test quality, or deciding what test would catch a bug. |
Write Tests
Use this skill when a change needs tests or when existing tests look too coupled
to implementation details.
Read root TESTING.md before writing or reviewing non-trivial tests. It is the
shared project-wide testing policy used by write-tests, review-pr, and
commit.
Also read the relevant module-specific docs before choosing test style,
fixtures, mocks, markers, or commands:
- root
AGENTS.md
- root
TESTING.md
- the nearest subproject
AGENTS.md for files under lib/*
- package testing docs referenced from that
AGENTS.md, such as
lib/iris/TESTING.md
Workflow
- Find existing tests for the touched behavior before creating a new file.
- Check module-specific testing rules for commands, markers, fakes, mocks, and
numerical tolerances.
- Name the behavior that should fail if the code is wrong.
- Write the smallest test that observes that behavior through a public API,
structured output, persisted state, or real side effect.
- Prefer a regression test before the fix when fixing a bug. Ensure the test fails before implementing the bug fix.
- Keep test setup realistic but small. Use fixtures and parameterization to
remove duplication.
- Run the narrow test first, then the relevant package test command. Before a
PR, run the repo lint entry point required by
AGENTS.md.
Default Commands
- Run a narrow test path while editing, then run
uv run --no-project infra/ci/run_tests.py. Do not override the repository's
default marker expression.
- For package-specific commands, use the relevant
lib/*/AGENTS.md or testing
doc.
For PR preparation, run ./infra/pre-commit.py --changed-files --fix or
./infra/pre-commit.py --all-files --fix as appropriate. Do not replace it
with uv run pre-commit.
