integers strategy can fail with assertion error: assert min_value is not None

[pspacek]

Versions tested

• hypothesis 6.100.4
• Python 3.12.3
• pytest 8.2.0

Summary

@given(i=integers()) exploded with assertion error on assert min_value is not None. Huh?

Reproducer

Trivial do-nothing test case:

from hypothesis import given, settings
from hypothesis.strategies import integers


@given(i=integers())
@settings(max_examples=50000)
def test_dummy(i):
    assert i is i

Run it with: pytest --hypothesis-seed=55662285600128535524272749666366957831 tgiven.py

On my machine it takes about 12 seconds until it asserts, but it asserts reliably.

Traceback

    @given(i=integers())
>   @settings(max_examples=50000)

tgiven.py:6: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib/python3.12/site-packages/hypothesis/internal/conjecture/engine.py:543: in run
    self._run()
/usr/lib/python3.12/site-packages/hypothesis/internal/conjecture/engine.py:973: in _run
    self.generate_new_examples()
/usr/lib/python3.12/site-packages/hypothesis/internal/conjecture/engine.py:755: in generate_new_examples
    prefix = self.generate_novel_prefix()
/usr/lib/python3.12/site-packages/hypothesis/internal/conjecture/engine.py:399: in generate_novel_prefix
    return self.tree.generate_novel_prefix(self.random)
/usr/lib/python3.12/site-packages/hypothesis/internal/conjecture/datatree.py:766: in generate_novel_prefix
    (v, buf) = self._draw_from_cache(
/usr/lib/python3.12/site-packages/hypothesis/internal/conjecture/datatree.py:904: in _draw_from_cache
    for v in generator:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

ir_type = 'integer', kwargs = {'max_value': None, 'min_value': None, 'shrink_towards': 0, 'weights': None}

    def all_children(ir_type, kwargs):
        if ir_type == "integer":
            min_value = kwargs["min_value"]
            max_value = kwargs["max_value"]
            weights = kwargs["weights"]
            # it's a bit annoying (but completely feasible) to implement the cases
            # other than "both sides bounded" here. We haven't needed to yet because
            # in practice we don't struggle with unbounded integer generation.
>           assert min_value is not None
E           assert None is not None

/usr/lib/python3.12/site-packages/hypothesis/internal/conjecture/datatree.py:270: AssertionError
============================================= short test summary info ==============================================
FAILED tgiven.py::test_dummy - assert None is not None

Debug log generated with pytest --hypothesis-verbosity=debug --full-trace --hypothesis-seed=55662285600128535524272749666366957831 tgiven.py &> debug.log is attached here:

debug.log.gz