python-dev

name	python-dev
description	Use when writing Python code, setting up tests with pytest, or configuring Python application deployment.
metadata	{"author":"skills-team"}

Python Development

When to Use

• Writing or reviewing Python code
• Setting up test infrastructure
• Containerizing/deploying Python applications

Invoke test-driven-development skill when implementing via TDD.

Patterns Summary

Problem	Solution
Type hints	Annotate function signatures
Internal containers	@dataclass
Runtime validation	Pydantic
Large datasets	Generators (lazy evaluation)
File paths	pathlib.Path
Preserving metadata	@functools.wraps

See references/patterns.md for detailed patterns.

Testing Summary

Pattern	Example
Fixtures	@pytest.fixture with yield for setup/teardown
Parametrization	@pytest.mark.parametrize
Mocking	@patch decorator
Running	pytest --cov=pkg, --lf (last-failed), -k "test_name"

See references/testing.md for complete testing guide.

Deployment Summary

Tool	Use
venv	Standard library
uv	Fast resolution (recommended)
pipx	Global CLI tools
pyproject.toml	Package definition

See references/deployment.md for Docker, Gunicorn/Uvicorn.

DO / DON'T

DO	DON'T
Type hints on signatures	Mutable defaults (def foo(x=[]))
is None check	== None
Generators for large data	Load all in memory
@functools.wraps in decorators	Share state between tests
Pin dependency versions	Use :latest Docker tags

References

• references/patterns.md - Type hints, dataclasses, decorators, pathlib
• references/testing.md - pytest fixtures, mocking, coverage
• references/deployment.md - Docker, servers, environment