Who is using Hypothesis?

This is a page for listing people who are using Hypothesis and how excited they are about that. If that’s you and your name is not on the list, this file is in Git and I’d love it if you sent me a pull request to fix that.

Kristian Glass - Director of Technology at LaterPay GmbH

Hypothesis has been brilliant for expanding the coverage of our test cases, and also for making them much easier to read and understand, so we’re sure we’re testing the things we want in the way we want.

Seth Morton

When I first heard about Hypothesis, I knew I had to include it in my two open-source Python libraries, natsort and fastnumbers . Quite frankly, I was a little appalled at the number of bugs and “holes” I found in the code. I can now say with confidence that my libraries are more robust to “the wild.” In addition, Hypothesis gave me the confidence to expand these libraries to fully support Unicode input, which I never would have had the stomach for without such thorough testing capabilities. Thanks!

Sixty North

At Sixty North we use Hypothesis for testing Segpy an open source Python library for shifting data between Python data structures and SEG Y files which contain geophysical data from the seismic reflection surveys used in oil and gas exploration.

This is our first experience of property-based testing – as opposed to example-based testing. Not only are our tests more powerful, they are also much better explanations of what we expect of the production code. In fact, the tests are much closer to being specifications. Hypothesis has located real defects in our code which went undetected by traditional test cases, simply because Hypothesis is more relentlessly devious about test case generation than us mere humans! We found Hypothesis particularly beneficial for Segpy because SEG Y is an antiquated format that uses legacy text encodings (EBCDIC) and even a legacy floating point format we implemented from scratch in Python.

Hypothesis is sure to find a place in most of our future Python codebases and many existing ones too.


Just found out about this excellent QuickCheck for Python implementation and ran up a few tests for my bytesize package last night. Refuted a few hypotheses in the process.

Looking forward to using it with a bunch of other projects as well.

Adam Johnson

I have written a small library to serialize dicts to MariaDB’s dynamic columns binary format, mariadb-dyncol. When I first developed it, I thought I had tested it really well - there were hundreds of test cases, some of them even taken from MariaDB’s test suite itself. I was ready to release.

Lucky for me, I tried Hypothesis with David at the PyCon UK sprints. Wow! It found bug after bug after bug. Even after a first release, I thought of a way to make the tests do more validation, which revealed a further round of bugs! Most impressively, Hypothesis found a complicated off-by-one error in a condition with 4095 versus 4096 bytes of data - something that I would never have found.

Long live Hypothesis! (Or at least, property-based testing).

Josh Bronson

Adopting Hypothesis improved bidict‘s test coverage and significantly increased our ability to make changes to the code with confidence that correct behavior would be preserved. Thank you, David, for the great testing tool.

Cory Benfield

Hypothesis is the single most powerful tool in my toolbox for working with algorithmic code, or any software that produces predictable output from a wide range of sources. When using it with Priority, Hypothesis consistently found errors in my assumptions and extremely subtle bugs that would have taken months of real-world use to locate. In some cases, Hypothesis found subtle deviations from the correct output of the algorithm that may never have been noticed at all.

When it comes to validating the correctness of your tools, nothing comes close to the thoroughness and power of Hypothesis.

Jon Moore

One extremely satisfied user here. Hypothesis is a really solid implementation of property-based testing, adapted well to Python, and with good features such as failure-case shrinkers. I first used it on a project where we needed to verify that a vendor’s Python and non-Python implementations of an algorithm matched, and it found about a dozen cases that previous example-based testing and code inspections had not. Since then I’ve been evangelizing for it at our firm.

Russel Winder

I am using Hypothesis as an integral part of my Python workshops. Testing is an integral part of Python programming and whilst unittest and, better, py.test can handle example-based testing, property-based testing is increasingly far more important than example-base testing, and Hypothesis fits the bill.

Wellfire Interactive

We’ve been using Hypothesis in a variety of client projects, from testing Django-related functionality to domain-specific calculations. It both speeds up and simplifies the testing process since there’s so much less tedious and error-prone work to do in identifying edge cases. Test coverage is nice but test depth is even nicer, and it’s much easier to get meaningful test depth using Hypothesis.

Your name goes here

I know there are many more, because I keep finding out about new people I’d never even heard of using Hypothesis. If you’re looking to way to give back to a tool you love, adding your name here only takes a moment and would really help a lot. As per instructions at the top, just send me a pull request and I’ll add you to the list.