Checkout Code Kata

This comes from the content from the following udemy course: https://www.udemy.com/course/unit-testing-and-tdd-in-python/

Setup & Run Tests

Install pipenv if you haven't already
Clone the repo
export PIPENV_VENV_IN_PROJECT=true to setup a virtual environment in the directory where you've cloned the repo
pipenv install --dev
source .venv/bin/activate
pytest -v --cov=checkout