pytest-antilru
Bust functools.lru_cache when running pytest to avoid test pollution
Decision gist · record as of 2026-08-14
Yes. This is a targeted fix for a real problem—test pollution from lru_cache—with low install friction, active maintenance, no vulnerabilities, and permissive licensing. If you use lru_cache in code under test and have experienced test ordering issues or mocking problems, this plugin eliminates the problem with zero code changes.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python >=3.9 and pytest >=3 (pytest <9 for Python 3.9, <10 for Python 3.10+).
- Low friction install as a pure Python wheel with only pytest as a runtime dependency.
- Active maintenance with a recent release (103 days ago) and no known vulnerabilities.
License · maintenance · safety
MIT (permissive) — MIT license permits unrestricted use, modification, and distribution in both open-source and proprietary projects.
last release 2026-05-03 (103 days) · last repo commit 2026-05-03 · 33 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 239,801 downloads/mo, #8,915 on PyPI
Alternatives
Verify before relying
pip install pytest-antilru
# Once installed, pytest automatically clears lru_cache between test runs.
# Optional: configure in pytest.ini to target specific modules:
# [tool.pytest.ini_options]
# lru_cache_disabled = 'my_module.util'- Whether disabling lru_cache globally (the default) impacts performance of the test suite itself.
- Behavior when lru_cache is used in third-party dependencies that expect caching to persist across test runs.
What it is and what it does
pytest-antilru is a pytest plugin that automatically clears functools.lru_cache between test runs. When you use lru_cache in your application code and then mock or patch dependencies in tests, the cache can retain stale values from previous test runs, causing tests to fail or pass unexpectedly depending on execution order. This plugin solves that by busting the cache between tests, restoring proper test isolation.
The plugin works automatically once installed—no code changes needed. By default it disables lru_cache everywhere, but you can configure an allowlist of specific module paths where caching should remain active, useful when other dependencies rely on cache behavior to function correctly within a single test run.
Use it for
- Testing functions that use lru_cache with mocked network calls or external dependencies that return different values across test cases.
- Ensuring test order independence when cached functions are involved, preventing flaky tests that pass or fail based on execution sequence.
- Selectively disabling cache for specific modules while preserving it in others to avoid breaking dependencies that rely on caching.
- Debugging test pollution issues caused by persistent cached state from previous test runs.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
This is a targeted fix for a real problem—test pollution from lru_cache—with low install friction, active maintenance, no vulnerabilities, and permissive licensing. If you use lru_cache in code under test and have experienced test ordering issues or mocking problems, this plugin eliminates the problem with zero code changes.
Install
pytest-antilru on PyPI
Before you install
Low friction install as a pure Python wheel with only pytest as a runtime dependency. Active maintenance with a recent release (103 days ago) and no known vulnerabilities.
Requires Python >=3.9 and pytest >=3 (pytest <9 for Python 3.9, <10 for Python 3.10+).
License in practice
MIT license permits unrestricted use, modification, and distribution in both open-source and proprietary projects.
Quickstart
pip install pytest-antilru
# Once installed, pytest automatically clears lru_cache between test runs.
# Optional: configure in pytest.ini to target specific modules:
# [tool.pytest.ini_options]
# lru_cache_disabled = 'my_module.util'Verify before relying
- Whether disabling lru_cache globally (the default) impacts performance of the test suite itself.
- Behavior when lru_cache is used in third-party dependencies that expect caching to persist across test runs.
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release >=3.9 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagepytest |
| Maintenance | Actively maintained 103 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 239,801 / month, #8,915 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableFramework :: PytestProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.9 |
Evidence: pytest_antilru-2.0.1-py2.py3-none-any.whl
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See also backports.functools-lru-cache · async-lru · methodtools · detect-test-pollution · cachebox · cachetools · onecache · functools32 · memoization · pytest-socket