Command Runner

We want to make it easy for Viewers to see the examples locally. In fact, to easily tinker with them and see changes.

Let’s add a CLI that fires up a web server.

CLI

I’ll use Typer to manage the CLI, with typer[all] as the installation to get Rich. I then add a single entry point in __main__.py and ensure it is registered in pyproject.toml. I then add a test in tests/test_main.py to ensure it works as expected.

This was a little tricky. I don’t want to actually run the server in the CLI and Typer spawns a subprocess, so I can’t mock (I think?) Thus, I added a CLI option I could pass in to prevent the server from starting.

With this, users can run, in their virtualenv once PSC is installed:

$ python -m psc

If you have pipx installed (and if PSC were actuall uploaded to PyPI):

$ pipx psc

I can run in my editable install:

$ poetry run python -m psc

Web App

I’ll use Starlette and uvicorn. In this step, it’s just one route which returns static HTML. I can test this easily using TestClient which requires an installation of requests.

:::{note} Nice way to run tests TestClient is nice because it doesn’t start an actual server. That’s a big part of the complaint on the current testing strategy for PyScript. The SimpleHTTPServer running in a thread is kind of fragile for getting hung. :::

Wrapup

I run pre-commit, mypy, and nox. Everything is good, onward.