Python Developer Tooling Handbook – Testing

Seven Claude Code Skills for Python from the Creator of spaCy

Tim Hopper — Mon, 16 Feb 2026 08:00:00 -0500

atthew Honnibal, co-founder of Explosion and creator of spaCy, has published a collection of Claude Code skills for Python development. It’s one of the more thoughtful skill collections I’ve seen.

Claude Code skills are markdown files you place in ~/.claude/commands/. When you type /<skill-name> in Claude Code, the file’s contents are injected as instructions. Think of them as reusable prompts that give Claude a specific methodology for a task, rather than leaving it to improvise.

Flexible Python Version Management with uv and tox

Tim Hopper — Wed, 12 Feb 2025 10:20:00 +0000

When working with Python projects that use tox for testing, you may encounter version mismatch errors like:

lint-format: skipped because could not find python interpreter with spec(s): python3.8

This happens when tox expects a specific Python version that isn’t available in your environment. Traditionally, this would require:

Effective Python Developer Tooling in December 2024

Tim Hopper — Fri, 20 Dec 2024 19:25:00 +0000

I have been writing Python for 14 years next month. When I started, people were still using easy_install to install egg-based packages for Python 2.7 and nobody had heard about Conda yet, much less uv. The Python tool ecosystem has changed since. Many people are confused by the fragmentation in the ecosystem, but we have better tooling for Python today than we’ve ever had before.

A friend recently invited me to give a talk to his team about Python tooling. In the presentation, I shared some principles of Python tooling and developer efficiency, some anti-patterns I’ve observed, recommended practices, and an opinionated list of tools I like in December 2024. What follows is a summary of that talk.