# Modern Python > Modern Python tooling and best practices using uv, ruff, ty, and pytest. Covers project setup with pyproject.toml (PEP 735), src layout, linting/formatting with ruff, type checking with ty, testing with pytest and coverage, pre-commit with prek, and security (pip-audit, detect-secrets, actionlint). Use when setting up or working on Python projects, replacing pip/virtualenv with uv, replacing flake8/black/mypy with ruff/ty, adding pre-commit or security scanning, or when the user mentions uv, ruff, ty, pytest, or cookiecutter-python patterns. Use when this capability is needed. - Skill: `tomevault-io/modern-python-2` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/modern-python-2` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/modern-python-2/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/modern-python-2 --- # Modern Python Modern Python tooling and practices: uv for dependencies, ruff for lint/format, ty for type checking, pytest for tests. Use for this project and when setting up or refactoring Python codebases. ## When to Use - Setting up or changing Python project structure and tooling - Replacing pip/virtualenv with uv - Replacing flake8/black/isort with ruff, or mypy with ty - Adding pre-commit hooks and security scanning - Writing or reviewing tests with pytest and coverage ## Legacy Command Guidance Prefer **uv** over raw `python`/`pip`. When about to run legacy commands, use: | Legacy command | Use instead | |----------------|-------------| | `python` | `uv run python` | | `python script.py` | `uv run script.py` | | `pip install pkg` | `uv add pkg` or `uv run --with pkg` | | `pip uninstall pkg` | `uv remove pkg` | | `pip freeze` | `uv export` | | `python -m pip install` | `uv add` / `uv sync` | Commands that already use `uv run` (e.g. `uv run pytest`) do not need changing. ## Project Structure and pyproject.toml - **Layout**: Prefer a `src/` layout (package under `src//`). This project uses top-level packages (`mcp_core`, `tools`, `ai_uml`); when adding new packages, keep them at repo root or under a clear namespace. - **Config**: Single `pyproject.toml` at repo root. - **Python**: Prefer Python 3.11+ in `[project]` for new projects; this repo uses 3.10+. - **Dependency groups** (PEP 735): Put dev/test/lint deps in dependency groups where the tool supports them. ## Linting and Formatting (ruff) - Use **ruff** for both linting and formatting (replaces flake8, black, isort, pyupgrade). - Configure in `pyproject.toml` under `[tool.ruff]` and `[tool.ruff.format]`. Run: - `uv run ruff check .` - `uv run ruff format .` Fix auto-fixable issues: `uv run ruff check --fix .` ## Type Checking (ty) - Use **ty** instead of mypy/pyright for faster type checking when introducing it. - Configure in `pyproject.toml` under `[tool.ty]` if needed. Run: `uv run ty check` ## Unit Testing (pytest) - Use **pytest** for all tests; prefer it over unittest for new code. - **Layout**: `tests/` at repo root; use `conftest.py` for shared fixtures. - **Coverage**: Use `pytest-cov`. Enforce a minimum coverage threshold so CI fails when coverage drops. Run: - `uv run pytest` - `uv run pytest --cov=mcp_core --cov=tools --cov-report=term-missing` - `uv run pytest -v tests/` **Good practices:** - Use `@pytest.fixture` for setup/teardown and shared state. - Use `@pytest.mark.parametrize` for multiple inputs/outputs. - Prefer descriptive test names and clear assertion messages. - Keep tests fast; use mocks for I/O or external services when appropriate. ## Pre-commit and Security - Use **prek** or **pre-commit** for hooks (ruff, ty, pytest, detect-secrets). - **Dependencies**: Run `uv run pip-audit` or use in CI. - **Secrets**: Use **detect-secrets** in pre-commit or CI. - **GitHub Actions**: Use **actionlint** for workflow syntax. ## Quick Checklist - [ ] Project uses `pyproject.toml` with clear `requires-python` and dependency groups - [ ] Dependencies managed with uv where possible; avoid bare `pip install` in instructions - [ ] Lint/format with ruff; type check with ty or mypy as configured - [ ] Tests with pytest; coverage enforced in config or CI - [ ] Pre-commit runs lint, format, and tests where appropriate - [ ] Security: pip-audit, detect-secrets; optional actionlint, Dependabot --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/antoinebou12) — claim your Tome and manage your conversions.