David R. MacIver's Blog

Hypothesis 1.8.0 is out

This release is mostly focused on internal refactoring, but has some nice polishing and a few bug fixes.

New features:

• Much more sensible reprs for strategies, especially ones that come from hypothesis.strategies. These should now have as reprs python code that would produce the same strategy.
• lists() accepts a unique_by argument which forces the generated lists to be only contain elements unique according to some function key (which must return a hashable value).
• Better error messages from flaky tests to help you debug things.

Mostly invisible implementation details that may result in finding new bugs in your code:

• Sets and dictionary generation should now produce a better range of results.
• floats with bounds now focus more on ‘critical values’, trying to produce values at edge cases.
• flatmap should now have better simplification for complicated cases, as well as generally being (I hope) more reliable.

Bug fixes:

• You could not previously use assume() if you were using the forking executor (because the relevant exception wasn’t pickleable).