ruff¶

A fast Python linter written in Rust. Like jarl for R, ruff is not a test framework: lint diagnostics map to warn events, clean files produce a synthetic pass, and lint issues appear alongside test results in the TUI and web dashboard. ruff is opt-in: enable it with an explicit [[suite]] tool = "ruff" entry in .scrutin/config.toml, or pass files on the command line with -t ruff in file mode.

Installing ruff¶

ruff is not shipped with Scrutin. Follow the upstream install instructions at docs.astral.sh/ruff.

Directory structure¶

myproject/
├── .scrutin/
│   └── config.toml     # [[suite]] tool = "ruff"
├── pyproject.toml      # optional: ruff's own config under [tool.ruff]
└── src/
    └── myproject/
        ├── __init__.py
        └── utils.py

Minimal example¶

.scrutin/config.toml

[[suite]]
tool = "ruff"

pyproject.toml (optional)

pyproject.toml's [tool.ruff] section, or a standalone ruff.toml / .ruff.toml at the suite root, is read by ruff itself (not by Scrutin) to tune rules:

[tool.ruff]
line-length = 88

Omit it to use ruff's built-in defaults.

src/myproject/utils.py

import os, sys  # E401: multiple imports on one line

def greet(name):
    x = 42  # F841: unused variable
    return f"hello, {name}"

Running¶

scrutin myproject              # TUI
scrutin -r plain myproject     # text output

ruff runs as its own suite alongside any other suites you've declared; suites run one at a time, but within the ruff suite every matched file is linted in parallel. It uses command mode (calling ruff check --output-format json directly), so no Python subprocess is needed.

Plugin actions¶

In the Detail view, ruff warnings show a numbered chip row of fix actions. Press the digit to invoke:

All four invoke ruff check --fix once with every matching file (after include / exclude filters) as trailing arguments. After a fix, the affected files are re-linted automatically.

Configuration¶

The minimal suite entry is just tool = "ruff". ruff's own configuration (ruff.toml, .ruff.toml, or [tool.ruff] in pyproject.toml) controls which rules are enabled, excluded paths, and other linter settings; Scrutin doesn't interpret it.

To override the default suite in .scrutin/config.toml:

[[suite]]
tool = "ruff"
# default `run` lints **/*.py under the suite root; `watch` defaults to `run`.
# Override to scope:
# run = ["src/**/*.py", "tests/**/*.py"]

ruff runs with cwd = suite.root so it picks up the local pyproject.toml / ruff.toml. Each file is checked independently, no dependency tracking.