# Projects extending Hypothesis

Hypothesis has been eagerly used and extended by the open source community. This page lists extensions and applications; you can find more or newer packages by searching PyPI by keyword or filter by classifier, or search libraries.io.

If there’s something missing which you think should be here, let us know!

Note

Being listed on this page does not imply that the Hypothesis maintainers endorse a package.

## External Strategies

Some packages provide strategies directly:

- hypothesis-fspaths - strategy to generate filesystem paths.
- hypothesis-geojson - strategy to generate GeoJson.
- hs-dbus-signature - strategy to generate arbitrary D-Bus signatures.
- hypothesis_sqlalchemy - strategies to generate SQLAlchemy objects.
- hypothesis-ros - strategies to generate messages and parameters for the Robot Operating System.
- hypothesis-csv - strategy to generate CSV files.
- hypothesis-networkx - strategy to generate networkx graphs.

Others provide a function to infer a strategy from some other schema:

- hypothesis-jsonschema - infer strategies from JSON schemas.
- lollipop-hypothesis - infer strategies from lollipop schemas.
- hypothesis-drf - infer strategies from a djangorestframework serialiser.
- hypothesis-mongoengine - infer strategies from a mongoengine model.
- hypothesis-pb - infer strategies from Protocol Buffer schemas.

## Other Cool Things

swagger-conformance is powered by Hypothesis and pyswagger. Based on a Swagger specification, it can build and run an entire test suite to check that the implementation matches the spec. The command-line version can test apps written in any language, simply by passing the file or URL path to the schema to check!

Trio is an async framework with “an obsessive focus on usability and correctness”, so naturally it works with Hypothesis! pytest-trio includes a custom hook that allows `@given(...)` to work with Trio-style async test functions, and hypothesis-trio includes stateful testing extensions to support concurrent programs.

libarchimedes makes it easy to use Hypothesis in the Hy language, a Lisp embedded in Python.

battle_tested is a fuzzing tool that will show you how your code can fail - by trying all kinds of inputs and reporting whatever happens.

pytest-subtesthack functions as a workaround for issue #377.

## Writing an Extension

See CONTRIBUTING.rst for more information.

New strategies can be added to Hypothesis, or published as an external package on PyPI - either is fine for most strategies. If in doubt, ask!

It’s generally much easier to get things working outside, because there’s more freedom to experiment and fewer requirements in stability and API style. We’re happy to review and help with external packages as well as pull requests!

If you’re thinking about writing an extension, please name it `hypothesis-{something}` - a standard prefix makes the community more visible and searching for extensions easier. And make sure you use the `Framework :: Hypothesis` trove classifier!

On the other hand, being inside gets you access to some deeper implementation features (if you need them) and better long-term guarantees about maintenance. We particularly encourage pull requests for new composable primitives that make implementing other strategies easier, or for widely used types in the standard library. Strategies for other things are also welcome; anything with external dependencies just goes in hypothesis.extra.