#2 - Setting Up a Python API Testing Project with uv

Understanding uv and its key advantages

What is uv?

uv is an extremely fast, modern Python package and project manager written in Rust, designed as an all-in-one replacement for existing tools like pip, virtualenv, pipx, and pyenv. uv promises dramatic performance gains and a simplified workflow for Python developers.

It consolidates multiple tools into a single, cohesive command-line interface — pip + venv + pip-tools + pipx, replaced by one fast tool.

It fully supports pyproject.toml for defining project metadata and dependencies, aligning with modern Python packaging standards.

Advantages

1. pyproject.toml as the source of truth
2. A lockfile (uv.lock) for deterministic installs
3. No need to "activate" a venv
4. Better dev vs. prod dependency separation

Essential uv commands for project setup

Setup uv and python

Install uv and update path:

curl -Ls https://astral.sh/uv/install.sh | bash

Verify uv is installed:

uv --version
uv 0.9.21

Install a Python version:

uv python install 3.14

List Python versions: uv python list

• Lists all Python interpreters uv can see (includes system-installed and uv-installed Python).
• uv separates system Python from project Python, so OS updates can't silently break your code or CI pipelines.
• uv python list always shows system-installed Python if no Python is installed via uv, because uv discovers and reuses what the OS already provides.
• Once you install Python via uv python install, uv prefers that version, but system Python remains visible as a fallback — not replaced.

Pin the project's Python version:

echo "3.13" > .python-version
cat .python-version

Initialize the project: uv init

Optionally update the project description in pyproject.toml:

Creating an API testing project using uv

Set up the virtual environment:

uv venv --python 3.13

Install packages:

uv add requests faker
uv add --group test pytest
uv add --dev black ruff mypy

After running the commands above, pyproject.toml is updated with the dependencies and uv.lock is created:

List dependencies: uv pip list

Reference

• GitHub — astral-sh/uv
• Installing and managing Python | uv