Hypothesis is the property-based testing library for Python. With Hypothesis, you write tests which should pass for all inputs in whatever range you describe, and let Hypothesis randomly choose which of those inputs to check - including edge cases you might not have thought about. For example:
from hypothesis import given, strategies as st
@given(st.lists(st.integers()))
def test_matches_builtin(ls):
assert sorted(ls) == my_sort(ls)This randomized testing can catch bugs and edge cases that you didn't think of and wouldn't have found. In addition, when Hypothesis does find a bug, it doesn't just report any failing example — it reports the simplest possible one. This makes property-based tests a powerful tool for debugging, as well as testing.
Recent Articles
If you watch the Hypothesis changelog, you'll notice the rate of releases sped up dramatically in 2017. We released over a hundred different versions, sometimes multiple times a day.
This is all thanks to our continuous release process. We've completely automated the process of releasing, so every pull request that …
Happy new year everybody!
In this post I'd like to tell you about one of the nice things that happened in 2017: The Hypothesis work that was funded by Smarkets Smarkets are an exchange for peer-to-peer trading of bets but, more importantly for us, they are fairly heavy users of …
In my last post I mentioned the problem of bug slippage: When you start with one bug, reduce the test case, and end up with another bug.
I've run into another related problem twice now, and it's not one I've seen talked about previously.
The problem is this: Sometimes shrinking …