Flexible Python Version Management with uv and tox

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:

1. Installing the required Python version
2. Creating a new virtualenv
3. Reinstalling dependencies
4. Running tox again

However, uv provides a more elegant solution through its tool isolation feature. By using uvx with the --python flag, you can run tox with any Python version on demand:

$ uvx --python 3.8 tox -e lint

This approach offers several advantages:

• No need to manage multiple virtualenvs
• Works with any Python version uv can access
• Maintains isolation between environments
• Zero configuration required