A `noxfile.py` for running matrix testing of a Python package

noxfile.py

import os
import time

import nox


@nox.session(python=["3.10", "3.11", "3.12"])
@nox.parametrize("django_constraint", ["<4.2", "<4.3", "<5.1"])
def tests(session: nox.Session, django_constraint: str) -> None:
    """
    Run the test suite with different Python and Django versions.
    """
    # Create a constraints file with the parameterized package versions.
    # It's easy to add more constraints here if needed.
    with open("constraints.txt", "w") as f:
        f.write(f"django{django_constraint}\n")

    # Install pip tools which we need to compile a new lock file.
    session.install("pip-tools==7.4.1")

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

    # Install the dependencies from the newly compiled lockfile and main package.
    session.install("-r", lockfile, ".")

    # When run in CircleCI, create JUnit XML test results.
    commands = ["pytest"]
    if "CIRCLECI" in os.environ:
        commands.append(f"--junitxml=test-results/junit.{session.name}.xml")

    session.run(*commands, *session.posargs)