Python Quality Checks

Run code quality tools on Python projects.

Quick Commands

Format Code (Black)

bash

black src/ tests/ --quiet

Lint Code (Ruff)

bash

ruff check src/ tests/ --fix

Type Check (Mypy)

bash

mypy src/

Run Tests (Pytest)

bash

pytest tests/ -v

All Checks (before committing)

bash

# If Makefile exists
make check

# Or manually
black src/ tests/ && ruff check src/ tests/ --fix && mypy src/ && pytest tests/

Usage Pattern

Before considering any Python coding task complete:

•Format: black src/
•Lint: ruff check src/ --fix
•Type check: mypy src/
•Test: pytest tests/

If any check fails, fix the issues before committing.

Tool Configs

Tools should be configured in pyproject.toml. Standard config:

toml

[tool.ruff]
target-version = "py39"
line-length = 100
select = ["E", "W", "F", "I", "B", "C4", "UP", "ARG", "SIM"]

[tool.black]
target-version = ["py39"]
line-length = 100

[tool.mypy]
python_version = "3.9"
disallow_untyped_defs = true
ignore_missing_imports = true

[tool.pytest.ini_options]
testpaths = ["tests"]
addopts = "-v --tb=short"

Fixing Common Issues

Ruff: Unused import

python

# ❌ F401: 'os' imported but unused
import os

# ✅ Remove unused imports, or:
import os  # noqa: F401  (if intentionally unused)

Mypy: Missing type annotation

python

# ❌ error: Function is missing a type annotation
def process(data):
    return data

# ✅ Add type hints
def process(data: dict[str, Any]) -> dict[str, Any]:
    return data

Black: Formatting

bash

# Auto-fixes formatting
black src/ --quiet

Integration with Coding Agents

When using Codex/Claude Code, add to the prompt:

code

After making changes, run:
1. black src/
2. ruff check src/ --fix
3. mypy src/
4. pytest tests/

Fix any issues before considering the task complete.