noxfile.py

"""
This `noxfile.py` is configured to run the test suite with multiple versions of Python and multiple
versions of Django (used as an example).
"""

import contextlib
import os
import tempfile
from typing import IO, Generator

import nox


# Use uv to manage venvs.
nox.options.default_venv_backend = "uv"


@contextlib.contextmanager
def temp_constraints_file() -> Generator[IO[str], None, None]:
    with tempfile.NamedTemporaryFile(
        mode="w", prefix="constraints.", suffix=".txt"
    ) as f:
        yield f


@contextlib.contextmanager
def temp_lock_file() -> Generator[IO[str], None, None]:
    with tempfile.NamedTemporaryFile(mode="w", prefix="packages.", suffix=".txt") as f:
        yield f


@nox.session()
@nox.parametrize(
    "dependency_file",
    [
        nox.param("pytest-in-nox-psycopg3", id="psycopg3"),
        nox.param("pytest-in-nox-psycopg2", id="psycopg2"),
    ],
)
@nox.parametrize(
    "package_constraint",
    [
        nox.param("django>=4.2,<4.3", id="django=4.2.X"),
        nox.param("django>=5.0,<5.1", id="django=5.0.X"),
    ],
)
@nox.parametrize(
    "python",
    [
        nox.param("3.10", id="python=3.10"),
        nox.param("3.11", id="python=3.11"),
        nox.param("3.12", id="python=3.12"),
    ],
)
def tests(session: nox.Session, package_constraint: str, dependency_file: str) -> None:
    """
    Run the test suite.
    """
    with temp_constraints_file() as constraints_file, temp_lock_file() as lock_file:
        # Create a constraints file with the parameterized package versions.
        # It's easy to add more constraints here if needed.
        constraints_file.write(f"{package_constraint}\n")
        constraints_file.flush()

        # Compile a new development lock file with the additional package
        # constraints from this session. Use a unique lock file name to avoid
        # session pollution.
        session.run(
            "uv",
            "pip",
            "compile",
            "--quiet",
            "--resolver=backtracking",
            "--strip-extras",
            f"--extra={dependency_file}",
            "pyproject.toml",
            "--constraint",
            constraints_file.name,
            "--output-file",
            lock_file.name,
        )

        # We have to open the file again since after `session.run` is
        # called, a `lock_file.write()` call won't write to the file anymore.
        with open(lock_file.name, "a") as f:
            # Add this project dependency to the lock file.
            f.write(".\n")

        # Use `uv sync` so that all packages that aren't included in the
        # dependency file are removed beforehand. This allow us to not end up
        # with two versions of a varying library (psycopg, for example).
        session.run("uv", "pip", "sync", lock_file.name)

    # Add the project directory to the PYTHONPATH for running the test Django
    # project.
    project_dir = os.path.abspath(".")
    session.env["PYTHONPATH"] = project_dir

    session.run("pytest", *session.posargs)