We now create the project you will use during the whole introduction. Every lesson ends with something you can add to it.

1. Create the project with uv
2. Run it
3. Open it in Zed
4. Add pytest and write your first test
5. Check your code with ruff and ty
6. Bonus: put it on GitHub

Open a terminal and go to the folder where you keep your stuff, for example Documents:

cd ~/Documents

Then let uv create the project and step into it:

uv init --no-package learn-python
cd learn-python

--no-package keeps things simple: your code lives right in the folder, in main.py. Without it, uv puts the code in a src/ folder instead, which you will meet in the last lesson.

uv made a folder with these files:

learn-python/
├── .git/              ← history of your changes (hidden folder)
├── .gitignore         ← files git should ignore
├── .python-version    ← which Python version this project uses
├── README.md          ← a description of the project
├── main.py            ← your program starts here
└── pyproject.toml     ← the project's name, settings and packages

uv run main.py

The first time, uv downloads Python and sets everything up. That can take a minute. Then you should see:

Hello from learn-python!

uv run is how we always start programs in this course. It makes sure the right Python and the right packages are used.

zed .

Open main.py in the file list on the left. Replace everything in it with this:

def greet(name: str) -> str:
    return f"Hello, {name}!"


def main() -> None:
    print(greet("pirate"))


if __name__ == "__main__":
    main()

Save with Ctrl + S (Mac: ⌘ + S) and run it again with uv run main.py.

A test is a small program that checks that your code works. Add pytest to the project:

uv add --dev pytest

Make a folder called tests with a file test_main.py inside:

from main import greet


def test_greet():
    assert greet("Ada") == "Hello, Ada!"

Add these two lines at the bottom of pyproject.toml, so pytest knows where your code lives:

[tool.pytest.ini_options]
pythonpath = ["."]

Now run the tests:

uv run pytest

You should see 1 passed in green. Try changing "Hello, Ada!" in the test and run it again. What happens?

ruff looks for mistakes and untidy code. ty checks that the types make sense.

ruff check .
ruff format .
ty check

Try to break something on purpose. In main.py, change the last line of greet to:

    return f"Hello, {name}!" + 1

Zed should underline it in red before you even run it. That is ty telling you that you cannot add a number to text. Change it back afterwards.

uv already prepared git for you. Save a snapshot of your project:

git add .
git commit -m "My first project"

You logged in with the GitHub CLI during setup, so one command creates the repository on GitHub and uploads your code:

gh repo create learn-python --source=. --public --push

Then open it in the browser:

gh repo view --web

Your code is online! 🎉 Next time you change something, it is just git add ., git commit -m "what I did" and git push.

If gh says you are not logged in, run gh auth login again like in the setup.