Setup pytest

We also want testing for our Python code, so let’s get pytest installed.

Install and Config

To start, we’ll add pytest to the dependencies in pyproject.toml. Really, they should go in dev dependencies, but this project really just a tutorial. Let’s go ahead and add all the dependencies we’ll need for the next few steps:

dependencies = [
    "sphinx",
    "myst-parser",
    "furo",
    "pytest",
    "playwright",
    "html5lib",
    "pytest-playwright",
    "starlette",
    "uvicorn",
    "watchfiles",
    "anyio",
    "httpx"
]

After adding, we do:

$ pip install -e .

We’ll also start the process of centralizing our pytest options. Instead of pytest.ini, we’ll use [tool.pytest.ini_options] in pyproject.toml. As an example, add this to pyproject.toml to configure strict marker usage in pytest:

[tool.pytest.ini_options]
addopts = "--strict-markers"

First Python Code and Test

As before, we’ll put a little tracer in our Python code and write a simple test.

In src/pyodide_components/__init__.py:

PYODIDE_COMPONENTS = "Hello"

Then, in tests/test_init.py:

from pyodide_components import PYODIDE_COMPONENTS


def test_hello():
    assert PYODIDE_COMPONENTS == "Hello"

Running pytest shows that the test passes.