Code Quality

HOPE uses automated tools to maintain code quality and consistent formatting.

Tools

Tool	Purpose
ruff	Python linter and formatter (replaces flake8, isort, black)
pre-commit	Git hooks for automated checks
mypy	Static type checking

Running Lint Checks

Using tox

tox -e lint

This runs all pre-commit hooks on all files, including: - ruff linting - ruff formatting - Other configured checks

Auto-fix Issues

tox -e clean

This automatically fixes: - Linting issues (where possible) - Code formatting

Pre-commit Hooks

Pre-commit runs checks automatically before each commit.

Installation

pre-commit install

Manual Run

# Run on all files
pre-commit run --all-files

# Run on staged files only
pre-commit run

# Run a specific hook
pre-commit run ruff --all-files

Configuration

Pre-commit hooks are configured in .pre-commit-config.yaml:

repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.11.8
    hooks:
      - id: ruff
        args: [--fix]
      - id: ruff-format

Ruff

Ruff is an extremely fast Python linter and formatter.

Running ruff Directly

# Check for issues
ruff check src tests

# Fix issues automatically
ruff check --fix src tests

# Format code
ruff format src tests

Configuration

Ruff is configured in ruff.toml:

line-length = 120
target-version = "py313"

[lint]
select = ["E", "F", "W", "I", "UP", "B", "C4", ...]
ignore = [...]

Type Checking with mypy

Running mypy

tox -e mypy

Or directly:

mypy src

Configuration

mypy is configured in mypy.ini:

[mypy]
python_version = 3.13
plugins = mypy_django_plugin.main

IDE Integration

VS Code

Install extensions: - Ruff (charliermarsh.ruff) - Pylance (ms-python.vscode-pylance)

Settings (.vscode/settings.json):

{
  "[python]": {
    "editor.defaultFormatter": "charliermarsh.ruff",
    "editor.formatOnSave": true,
    "editor.codeActionsOnSave": {
      "source.fixAll": "explicit",
      "source.organizeImports": "explicit"
    }
  }
}

PyCharm

1. Go to Settings > Plugins
2. Install Ruff plugin
3. Enable Ruff in Settings > Tools > Ruff

Common Issues

Import Order

Ruff automatically sorts imports. If you see import order errors:

ruff check --fix --select I src

Line Length

Default line length is 120 characters. Long lines will be flagged:

ruff check --select E501 src

Unused Imports

ruff check --select F401 --fix src

CI/CD

Lint checks run automatically in CI. PRs must pass all lint checks to be merged.

The CI runs:

tox -e lint

Ensure you run this locally before pushing to avoid CI failures.