Add Minimum Job

Adding a Minimum Version Job to Noxfile

This skill helps you add a minimums session to your project's noxfile.py that tests your package with the lowest direct dependencies. This is useful for verifying that your package's declared minimum version constraints are correct.

Before You Start

Prerequisites

• Your project must have a noxfile.py file
• uv should be installed (for the uv venv backend)
• nox should be available

Check Current Setup

Verify your noxfile doesn't already have a minimum version test:

grep -E "@nox\.session.*minimum|@nox\.session.*mintest" noxfile.py

If a session already exists, you may want to update it instead of creating a new one.

Step-by-Step Guide

1. Understanding the Minimum Job

The minimum version job:

• Uses uv as the venv backend for fast environment creation
• Installs dependencies with --resolution=lowest-direct to get the minimum allowed versions
• Runs your test suite to ensure it works with minimum versions
• Helps catch cases where your version constraints are too loose

2. Add the Session to Your Noxfile

Add this session to your noxfile.py. The exact placement and details depend on your project structure. Compare to the main "tests" or similar job.

Basic version (for projects using dependency-groups):

@nox.session(venv_backend="uv", default=False)
def minimums(session: nox.Session) -> None:
    """
    Test the minimum versions of dependencies.
    """
    session.install("-e.", "--group=test", "--resolution=lowest-direct")
    session.run("pytest", *session.posargs)

For projects without dependency-groups (legacy approach):

@nox.session(venv_backend="uv", default=False)
def minimums(session: nox.Session) -> None:
    """
    Test with minimum versions of all dependencies.
    """
    session.install("-e.[test]", "--resolution=lowest-direct")  # Adjust extras as needed
    session.run("pytest", *session.posargs)

3. Choose Your Configuration

The best configuration depends on your project. Consider:

• Do you use dependency-groups? Use --group=test approach
• Do you use extras? Use -e.[test] approach
• Do you need to test a specific Python version? Specify python=VERSION
• Do you need binary-only installations? Add --only-binary=:all:

4. Optional Enhancements

Show installed versions:

session.run("uv", "pip", "list")

This helps debug version resolution issues.

Set coverage reporting (if using coverage):

session.install("-e.", "--group=test", "--resolution=lowest-direct")
session.run("pytest", "--cov", "--cov-report=xml", *session.posargs)

5. Test Your New Session

Run your new session to verify it works:

# Run the minimums job
nox -s minimums

# Run with specific tests
nox -s minimums -- tests/test_core.py

# Run with pytest options
nox -s minimums -- -v -k specific_test

6. Verify Results

Check that:

• The session completes successfully
• Tests pass with minimum versions
• The reported installed versions are at or near your declared minimums

If tests fail:

1. The failure message will tell you which dependency has the problem
2. Check your pyproject.toml or setup.py for the version constraint
3. Either update the constraint to match what works, or update your code to handle the older version

7. Add to CI/CD

Consider adding the minimum version job to your GitHub Actions workflow:

- name: Run minimum versions test
  run: nox -s minimums

This ensures minimum versions stay valid on every commit.

Common Issues

Issue: Resolution fails or conflicts occur

Solution: This usually means your version constraints are too loose. Review the error message and update minimum versions in pyproject.toml.

Issue: Some tests fail with minimum versions

Solution: Your code may be using features only available in newer versions. Either:

1. Update your code to work with the minimum version
2. Increase the minimum version constraint

Issue: --resolution=lowest-direct is not recognized

Solution: You need to use the uv backend.

Examples from Real Projects

pypa/pyproject-metadata

Uses dependency-groups and shows installed versions:

@nox.session(venv_backend="uv", default=False, python=ALL_PYTHONS)
def minimums(session: nox.Session) -> None:
    """
    Check minimum requirements.
    """
    test_grp = nox.project.dependency_groups(PYPROJECT, "test")
    session.install("-e.", "--resolution=lowest-direct", *test_grp, silent=False)
    xmlcov_output = (
        Path(session.virtualenv.location) / f"coverage-{session.python}-min.xml"
    )
    session.run(
        "pytest",
        "--cov",
        f"--cov-report=xml:{xmlcov_output}",
        "--cov-report=term-missing",
        "--cov-context=test",
        "tests/",
        *session.posargs,
    )

scikit-hep/hist

Simple and direct:

@nox.session(venv_backend="uv", default=False)
def minimums(session):
    """
    Run with the minimum dependencies.
    """
    session.install("-e.", "--group=test", "--resolution=lowest-direct")
    session.run("uv", "pip", "list")
    session.run("pytest", *session.posargs)

scikit-hep/iminuit

Tests the minimum Python version with minimum dependencies:

@nox.session(python=MINIMUM_PYTHON, venv_backend="uv")
def mintest(session: nox.Session) -> None:
    """Run tests on the minimum python version."""
    session.install("--only-binary=:all:", "-e.", "--resolution=lowest-direct")
    session.install("pytest", "pytest-xdist")
    extra_args = session.posargs if session.posargs else ("-n=auto",)
    session.run("pytest", *extra_args)

Verification Checklist

After adding the minimum version job:

• [ ] nox -s minimums runs without errors
• [ ] All tests pass with minimum versions
• [ ] uv pip list (or pip list) shows versions at or near minimums
• [ ] CI/CD passes (if integrated)
• [ ] Version constraints in pyproject.toml are accurate

See Also

• Nox documentation
• Scientific Python Developer Guide
• uv documentation
• PEP 440: Version Identification

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: henryiii
• Source: henryiii/skills
• License: MIT

Install and usage instructions live in the source repository linked above.