hypothesis
The property-based testing library for Python
Decision gist · record as of 2026-08-14
Yes. Hypothesis is production-ready (Development Status 5 - Production/Stable), actively maintained, and has zero known vulnerabilities. The medium install friction is negligible given its two lightweight dependencies. MPL-2.0 copyleft is standard for testing tools and poses no practical barrier for most projects. Install it if you want to catch bugs your manual tests miss.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later.
- Medium install friction with two lightweight runtime dependencies (exceptiongroup, sortedcontainers).
- Active maintenance with a release 2 days old and 8884 repository stars.
License · maintenance · safety
MPL-2.0 (copyleft) — Licensed under MPL-2.0 (copyleft). You may use and modify Hypothesis freely, but modifications and derivative works must be distributed under the same license if distributed at all.
last release 2026-08-12 (2 days) · last repo commit 2026-08-14 · 8,884 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 48,260,681 downloads/mo, #595 on PyPI
Alternatives
Verify before relying
pip install hypothesis
from hypothesis import given, strategies as st
@given(st.lists(st.integers()))
def test_my_function(data):
assert my_function(data) == expected_result(data)- Whether the optional extras mentioned in the description are documented and what they provide.
- Performance characteristics when testing with very large input spaces or complex strategies.
- Actual adoption scale and real-world usage patterns beyond download metrics.
What it is and what it does
Hypothesis is a property-based testing framework that inverts the typical testing model: instead of writing specific test cases, you describe the range of valid inputs and write a test that should pass for all of them. Hypothesis then generates random inputs within that range, including edge cases you might not have anticipated, and runs your test against each one. When it finds a failure, it doesn't just report any failing input—it automatically shrinks the input to the simplest possible case that still fails, making debugging much faster.
The library is built on two runtime dependencies (exceptiongroup and sortedcontainers) and integrates with test frameworks. It's actively maintained, supports Python 3.10 and later across CPython and PyPy implementations, and carries no known security vulnerabilities.
Use it for
- Discover edge cases in sorting, parsing, or data transformation functions that manual test cases would miss.
- Test API handlers or business logic against a wide range of valid input combinations automatically.
- Debug complex bugs by letting Hypothesis find and minimize the simplest failing input.
- Verify mathematical properties or invariants hold across large input domains.
- Generate test data for integration tests without hand-writing hundreds of specific cases.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Hypothesis is production-ready (Development Status 5 - Production/Stable), actively maintained, and has zero known vulnerabilities. The medium install friction is negligible given its two lightweight dependencies. MPL-2.0 copyleft is standard for testing tools and poses no practical barrier for most projects. Install it if you want to catch bugs your manual tests miss.
Install
hypothesis on PyPI
Before you install
Medium install friction with two lightweight runtime dependencies (exceptiongroup, sortedcontainers). Active maintenance with a release 2 days old and 8884 repository stars. Supports Python 3.10 and later across CPython and PyPy, with wheels available for all major platforms.
Requires Python 3.10 or later.
License in practice
Licensed under MPL-2.0 (copyleft). You may use and modify Hypothesis freely, but modifications and derivative works must be distributed under the same license if distributed at all.
Quickstart
pip install hypothesis
from hypothesis import given, strategies as st
@given(st.lists(st.integers()))
def test_my_function(data):
assert my_function(data) == expected_result(data)Verify before relying
- Whether the optional extras mentioned in the description are documented and what they provide.
- Performance characteristics when testing with very large input spaces or complex strategies.
- Actual adoption scale and real-world usage patterns beyond download metrics.
Package facts
| License | MPL-2.0 copyleft |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Medium. Platform-specific wheel |
| Runtime dependencies | 2 packagesexceptiongroupsortedcontainers |
| Maintenance | Actively maintained 2 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 48,260,681 / month, #595 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 :: HypothesisFramework :: PytestIntended Audience :: DevelopersOperating System :: Microsoft :: WindowsOperating System :: POSIXOperating System :: UnixProgramming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyTopic :: Education :: TestingTopic :: Software Development :: TestingTyping :: Typed |
Evidence: hypothesis-6.165.5-cp310-abi3-macosx_10_12_x86_64.whl; hypothesis-6.165.5-cp310-abi3-macosx_11_0_arm64.whl; hypothesis-6.165.5-cp310-abi3-manylinux_2_17_aarch64.manylinux2014_aarch64.whl; hypothesis-6.165.5-cp310-abi3-manylinux_2_17_armv7l.manylinux2014_armv7l.whl; hypothesis-6.165.5-cp310-abi3-manylinux_2_17_x86_64.manylinux2014_x86_64.whl; hypothesis-6.165.5-cp310-abi3-manylinux_2_31_riscv64.whl; hypothesis-6.165.5-cp310-abi3-manylinux_2_5_i686.manylinux1_i686.whl; hypothesis-6.165.5-cp310-abi3-musllinux_1_2_aarch64.whl; hypothesis-6.165.5-cp310-abi3-musllinux_1_2_armv7l.whl; hypothesis-6.165.5-cp310-abi3-musllinux_1_2_riscv64.whl; hypothesis-6.165.5-cp310-abi3-musllinux_1_2_x86_64.whl; hypothesis-6.165.5-cp310-abi3-win32.whl; hypothesis-6.165.5-cp310-abi3-win_amd64.whl; hypothesis-6.165.5-cp310-cp310-macosx_10_12_x86_64.whl; hypothesis-6.165.5-cp310-cp310-macosx_11_0_arm64.whl; hypothesis-6.165.5-cp310-cp310-manylinux_2_17_aarch64.manylinux2014_aarch64.whl; hypothesis-6.165.5-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl; hypothesis-6.165.5-cp310-cp310-musllinux_1_2_aarch64.whl; hypothesis-6.165.5-cp310-cp310-musllinux_1_2_x86_64.whl; hypothesis-6.165.5-cp310-cp310-win_amd64.whl
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