pytest-lazy-fixtures

What it is and what it does

pytest-lazy-fixtures extends pytest's parametrize decorator to accept fixture references as parameter values, solving the limitation that fixtures cannot normally be used directly in @pytest.mark.parametrize. It provides two main tools: lf (lazy_fixture) for simple fixture references and lfc (lazy_fixture_callable) for wrapping callables that should receive fixture values. The package supports fixtures nested in data structures (lists, dicts, tuples), attribute access via dot notation (e.g., lf('fixture.attr')), and automatic parameter injection based on callable signatures.

The package depends only on pytest and is compatible with other pytest plugins. It targets Python 3.8 and above and is distributed under the MIT license, making it suitable for most projects.

Use it for:

• Parametrize tests with fixture-derived values without duplicating fixture logic in test parameters.
• Test multiple scenarios where each scenario needs a fresh instance of a complex fixture object.
• Build parametrized test cases that reference fixture attributes or call fixture methods.
• Use fixtures as arguments to custom callables within parametrize, enabling flexible test data composition.

Worth the install?

AI-flagged interpretation of the facts on this page — verify before relying

Allows you to reference pytest fixtures directly within @pytest.mark.parametrize decorators, including nested data structures and fixture attributes.

Yes. The package solves a genuine pytest limitation with low install friction, active maintenance, no known vulnerabilities, and a permissive MIT license. It is well-suited for projects that need to parametrize tests with fixture-derived values.

Install

pytest-lazy-fixtures on PyPI

pip install pytest-lazy-fixtures

uv add pytest-lazy-fixtures

poetry add pytest-lazy-fixtures

Installing pytest-lazy-fixtures

Before you install

Low friction install with a single runtime dependency on pytest. Actively maintained with last commit 2026-08-12 and 113 repository stars.

License in practice

MIT license permits free use, modification, and distribution with minimal restrictions—suitable for both open-source and commercial projects.

Quickstart

pip install pytest-lazy-fixtures

import pytest
from pytest_lazy_fixtures import lf

@pytest.fixture()
def one():
    return 1

@pytest.mark.parametrize('arg1,arg2', [('val1', lf('one'))])
def test_func(arg1, arg2):
    assert arg2 == 1

Requires pytest as a runtime dependency.

Verify before relying

• Whether implicit fixture injection from callable signatures works reliably across all pytest versions.
• Performance impact when parametrizing tests with large numbers of lazy fixture references.

Package facts

Evidence: pytest_lazy_fixtures-1.4.1-py3-none-any.whl

Keywords: fixture, lazy, pytest, tests

Tags

More Testing packages