pytest-freezegun

library0.4.2pypypi✓ verified 25d ago

pytest-freezegun is a pytest plugin that simplifies testing time-dependent code by integrating the `freezegun` library with pytest fixtures and marks. It allows you to freeze time during test execution using either a decorator or a dedicated fixture. The current version is 0.4.2, and it maintains a moderate release cadence, addressing compatibility and feature improvements.

testing

pip install pytest-freezegun

github ↗package ↗

INSTALL

IMPORT

SIG · PYTEST-FREEZEGUN

pytest-freezegun

testingpythonv0.4.2

Install

2.9s avg

Import

—

Disk

31MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.4.2 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.000s · 32.1MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 2.9s · import 0.000s · 33MB

31MB installed

● package 31MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

pytest.mark.freeze_time

✓ import pytest # accessed via pytest.mark

The 'freeze_time' mark is registered by the plugin and accessed via `pytest.mark`, not directly imported.

freezer (fixture)

✓ def test_example(freezer):

The 'freezer' fixture is automatically provided by the plugin.

This quickstart demonstrates the two primary ways to freeze time with pytest-freezegun: using the `pytest.mark.freeze_time` decorator for a static time freeze on a test function, and using the `freezer` fixture to dynamically control time within a test, including advancing it.

import datetime import pytest @pytest.mark.freeze_time("2023-01-15 12:00:00") def test_frozen_time_decorator(): assert datetime.datetime.now() == datetime.datetime(2023, 1, 15, 12, 0, 0) def test_frozen_time_fixture(freezer): freezer.move_to("2024-02-29 10:30:00") assert datetime.datetime.now() == datetime.datetime(2024, 2, 29, 10, 30, 0) freezer.tick(datetime.timedelta(hours=1)) assert datetime.datetime.now() == datetime.datetime(2024, 2, 29, 11, 30, 0)

Debug

Known issues

breakingPython 3.5 and older are no longer supported. Versions prior to 0.4.1 dropped support for Python < 3.5. Version 0.3.0 dropped support for Python 3.3.

fix

Upgrade to Python 3.6+ to use pytest-freezegun 0.4.1+.

affects: <0.4.1

gotchaThe `freeze_time` mark was not automatically registered as a known mark in versions prior to 0.4.1. This could lead to pytest warnings about unknown marks.

fix

Upgrade to pytest-freezegun 0.4.1+ or explicitly register the mark in your `pytest.ini` using `markers = freeze_time`.

affects: <0.4.1

gotchaWhen both `@pytest.mark.freeze_time` and the `freezer` fixture are used in the same test or test scope, there were issues in older versions where `freeze_time` might not correctly freeze time in fixtures, or `freezer.move_to` might override unexpected values.

fix

Upgrade to pytest-freezegun 0.4.2+ which includes fixes for this interaction. Always ensure `freezer.move_to()` is called after `freeze_time` if dynamic adjustment is needed within a marked test.

affects: <0.4.2

gotchaSupport for class-based tests (e.g., using `@pytest.mark.freeze_time` on a test method within a class) was added in 0.4.1. Earlier versions might not apply the time freeze correctly to methods within test classes.

fix

Upgrade to pytest-freezegun 0.4.1+ for reliable support with class-based tests.

affects: <0.4.1

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'pytest_freezegun'

The 'pytest-freezegun' package is not installed in the Python environment.

fix

Install the package using pip: 'pip install pytest-freezegun'.

AttributeError: module 'freezegun' has no attribute 'freeze_time'

The 'freezegun' package is not installed or not properly imported.

fix

Ensure 'freezegun' is installed ('pip install freezegun') and correctly imported: 'from freezegun import freeze_time'.

TypeError: freeze_time() missing 1 required positional argument: 'time_to_freeze'

The 'freeze_time' decorator is used without specifying the time to freeze.

fix

Provide a time string to the decorator: '@freeze_time("2023-01-01")'.

ValueError: Invalid time format: 'invalid-date'

An incorrect date format is passed to the 'freeze_time' decorator.

fix

Use a valid date format, such as 'YYYY-MM-DD': '@freeze_time("2023-01-01")'.

ImportError: cannot import name 'freeze_time' from 'freezegun'

The 'freezegun' package is not installed or the import statement is incorrect.

fix

Ensure 'freezegun' is installed ('pip install freezegun') and import it correctly: 'from freezegun import freeze_time'.

Upgrade

Version history

0.4.2latest on PyPI · released Jul 19, 2020

Audit

Dependencies

pytestrequiredCore testing framework pytest-freezegun extends.

freezegunrequiredThe underlying library used for time freezing.

Agent activity

10 hits · last 30 days

node

Resources

githubhttps://github.com/ktosiek/pytest-freezegun ↗

packagehttps://pypi.org/project/pytest-freezegun/ ↗