Hypothesis

Overview

Hypothesis is ranked #2 of 27 in property-based testing tools on Specifiction. It runs on Linux, macOS, Windows.

Compared on property-based testing tools

Free plan

Yeshypothesis.works

Supported languages

Pythonhypothesis.works

Test runner support

pytest, unittesthypothesis.works

Failing-case shrinking

Yeshypothesis.works

Stateful testing

Yeshypothesis.works

Reproducible failures

Yeshypothesis.works

Facts

What it does

Hypothesis is a property-based testing library for Python that generates inputs, including edge cases, to test properties you describe.hypothesis.works · 28 Sept 2026

Simplifies failures

When Hypothesis finds a bug, it reports a failing example and tries to simplify it.hypothesis.works · 28 Sept 2026

Test framework support

Hypothesis works with pytest, unittest, nose, or another framework that can run a Python function.hypothesis.works · 28 Sept 2026

Data generation

Its strategies let users describe and compose the kinds of data their tests should generate.hypothesis.works · 28 Sept 2026

Repeatable failures

Hypothesis saves failing examples in a local test database so it can replay them when tests run again.hypothesis.works · 28 Sept 2026

Test runner limitation

Hypothesis is not itself a test runner; it works inside a user's normal testing framework.hypothesis.works · 28 Sept 2026

Thread safety

As of version 6.136.9, Hypothesis supports running the same test simultaneously from multiple threads.hypothesis.works · 28 Sept 2026

Release availability

The project describes publishing new packages to PyPI after changes are merged, usually within half an hour.hypothesis.works · 28 Sept 2026

Intended users

Hypothesis is for people writing software tests who want to describe acceptable behavior and have the computer explore inputs.hypothesis.works · 28 Sept 2026

Edge cases

Hypothesis randomly chooses inputs, including edge cases the user may not have considered.hypothesis.works · 29 Sept 2026

Test runners

Hypothesis tests can run as regular Python functions and work with pytest or unittest.hypothesis.readthedocs.io · 29 Sept 2026

Default run count

By default, Hypothesis generates 100 random inputs per test, and this count can be controlled with the max_examples setting.hypothesis.readthedocs.io · 29 Sept 2026

Integrations

First-party extras include integrations for specific packages, and the documentation gives Django as an example installable extra.hypothesis.readthedocs.io · 29 Sept 2026

Operating systems

The project says it is known to work and regularly tested on macOS, Windows, Linux, and Emscripten.hypothesis.readthedocs.io · 29 Sept 2026

Python support

Hypothesis is supported and tested on CPython and PyPy 3.10 and later.hypothesis.readthedocs.io · 29 Sept 2026

Community help

Users can ask questions using the python-hypothesis Stack Overflow tag or join the mailing list for help and discussion.hypothesis.readthedocs.io · 29 Sept 2026

Compatibility limit

The project supports only the most recent Hypothesis version; documented APIs are not expected to break except between major version bumps, while undocumented behavior may break in patch releases.hypothesis.readthedocs.io · 29 Sept 2026

Development model

The maintainers say new features must be sponsored or implemented by someone else, and the project has no long-term release plan.hypothesis.readthedocs.io · 29 Sept 2026

Where it ranks on Specifiction

• Best Property-Based Testing Tools in 2026#2 of 27

Sources

• hypothesis.works· checked 28 Sept 2026
• hypothesis.works/articles/what-is-hypothesis/· checked 28 Sept 2026
• hypothesis.works/articles/thread-safe/· checked 28 Sept 2026
• hypothesis.works/articles/continuous-releases/· checked 28 Sept 2026
• hypothesis.readthedocs.io/en/latest/quickstart.html· checked 29 Sept 2026
• hypothesis.readthedocs.io/en/latest/extras.html· checked 29 Sept 2026
• hypothesis.readthedocs.io/en/latest/compatibility.html· checked 29 Sept 2026
• hypothesis.readthedocs.io/en/latest/community.html· checked 29 Sept 2026
• hypothesis.readthedocs.io/en/latest/development.html· checked 29 Sept 2026