Python packages & environments

Managing dependencies and virtual environments

This course uses a small set of Python libraries for testing and data processing. To keep your system clean and avoid version conflicts, we recommend using a virtual environment.

📦 Installing core packages

Once your environment is active (see below), you can install the required libraries directly using pip or uv.

The essentials

We primarily use three packages throughout the Python portion of the course:

# Using standard pip
pip install pytest pytest-cov requests

# Using uv (recommended)
uv pip install pytest pytest-cov requests

pytest: The industry-standard testing framework.
pytest-cov: Tools for measuring how much of your code is covered by tests.
requests: The “HTTP for Humans” library used for interacting with web APIs.

🛠️ Virtual environments

A virtual environment is an isolated space where you can install packages without affecting other projects or your global Python installation. Always create one for your lab repository.

Option 1: Using `uv` (recommended)

uv is an extremely fast Python package manager written in Rust. It is significantly faster than standard tools and handles environment creation automatically.

# 1. Install uv (one-time setup)
# macOS/Linux: curl -LsSf https://astral-sh.github.io/uv/install.sh | sh
# Windows: powershell -c "irm https://astral-sh.github.io/uv/install.ps1 | iex"

# 2. Create and activate a venv
uv venv
source .venv/bin/activate  # macOS/Linux
source .venv/Scripts/activate # Windows (Git Bash)

Option 2: Using `venv` (built-in)

If you prefer not to install extra tools, you can use Python’s built-in module:

# 1. Create the environment
python -m venv venv

# 2. Activate it
source venv/bin/activate  # macOS/Linux
source venv/Scripts/activate # Windows (Git Bash)

💡 Tips for success

Activation is key: Remember to activate your environment every time you open a new terminal window. You’ll know it’s active if you see (venv) or (.venv) in your command prompt.
VS Code integration: When you open your repository, VS Code will usually detect your virtual environment. Always click Yes when it asks to set it as the workspace interpreter.
Don’t commit your venv: Your environment folder contains thousands of files. It should never be pushed to GitHub. Our lab templates include this in the .gitignore by default.

Pro tip: Why use a requirements file?

While direct installation is fine for this course, professional projects use a requirements.txt file to ensure every developer on a team is using the exact same versions of every library. It’s the “recipe” for your project’s environment!