Hypothesis is a Python library for property-based testing; creating unit tests with pseudo-randomly generated data.
Questions about the testing library Hypothesis:
Questions tagged [python-hypothesis]
182 questions
5
votes
1 answer
Suppressing HealthCheck.too_slow for a composite hypothesis strategy
I have a number of unit tests that leverage a @composite strategy that I wrote. The strategy is quite slow (it generates complex objects) and from time to time one of the tests fails the too_slow health check. When that happens, I take a deep sigh…
Arek' Fu
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5
votes
2 answers
Python Hypothesis: How to compose generators that are dependent on each other?
I have a generator using python Hypothesis like the following:
@st.composite
def generate_network_fault_only(draw):
fault = {
"impaired": st.just(True), # need to detect if all faults are None to switch this back.
"limit":…
Mark Lakewood
- 133
- 6
4
votes
1 answer
Exception handling and testing with pytest and hypothesis
I'm writing tests for a statistical analysis with hypothesis. Hypothesis led me to a ZeroDivisionError in my code when it is passed very sparse data. So I adapted my code to handle the exception; in my case, that means log the reason and reraise…
suvayu
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4
votes
1 answer
Hypothesis equivalent of QuickCheck frequency generator?
As a learning project I am translating some Haskell code (which I'm unfamiliar with) into Python (which I know well)...
The Haskell library I'm translating has tests which make use of QuickCheck property-based testing. On the Python side I am using…
Anentropic
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4
votes
1 answer
How do I set the minimum and maximum length of dataframes in hypothesis?
I have the following strategy for creating dataframes with genomics data:
from hypothesis.extra.pandas import columns, data_frames, column
import hypothesis.strategies as st
def mysort(tp):
key = [-1, tp[1], tp[2], int(1e10)]
return [x…
The Unfun Cat
- 29,987
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4
votes
1 answer
test isolation between pytest-hypothesis runs
I just migrated a pytest test suite from quickcheck to hypothesis. This worked quite well (and immediately uncovered some hidden edge case bugs), but one major difference I see is related to test isolation between the two property…
Bart Van Loon
- 1,430
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4
votes
1 answer
Generate string data from regex
I would like to be able to take a regex and generate conforming data using the python hypothesis library. For example given a regex of
regex = re.compile('[a-zA-Z]')
This would match any english alpha characters. An example generator for this…
Mark Lakewood
- 133
- 6
4
votes
2 answers
Random sampling with Hypothesis
In Hypothesis, there is an corresponding sampled_from() strategy to random.choice():
In [1]: from hypothesis import find, strategies as st
In [2]: find(st.sampled_from(('ST', 'LT', 'TG', 'CT')), lambda x: True)
Out[2]: 'ST'
But, is there a way to…
alecxe
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votes
3 answers
How to enforce relative constraints on hypothesis strategies?
Say I have 2 variables a and b where it is given that b > a, how then can I enforce this relative constraint on the hypothesis strategies?
from hypothesis import given, strategies as st
@given(st.integers(), st.integers())
def test_subtraction(a,…
MShakeG
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3
votes
1 answer
Multiple strategies for same function parameter in python hypothesis
I am writing a simple test code in Python using the Hypothesis package. It there a way to use multiple strategies for the same function parameter? As an example, use integers() and floats() to test my values parameter without writing two separate…
Mattia Surricchio
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3
votes
1 answer
How can I generate a hypothesis strategy to generate a list that contains at least one of each element it samples from?
I am looking for a way to build a Hypothesis strategy such that each element in a given list is present in the generated list.
e.g.
Assuming that we have
values = [0, 1, 2, 3, 5, 8]
we want a strategy that generates lists from given values such…
tschlich
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3
votes
1 answer
Using given with parametrize
I was wondering if it is possible to use given with parameters comes from pytest's parametrize function.
Example:
import pytest
from hypothesis import given
from hypothesis import strategies as st
@st.composite
def my_strategy(draw, attribute):
…
UdiM
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3
votes
2 answers
Hypothesis strategy generating inf when specifically asked not to
from functools import partial
import hypothesis as h
import hypothesis.strategies as hs
import hypothesis.extra.numpy as hnp
import numpy as np
floats_notnull = partial(hs.floats, allow_nan=False, allow_infinity=False)
complex_notnull =…
shadowtalker
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3
votes
1 answer
Hypothesis stateful testing with pytest.raises doesn't report sequence of steps
I want to write a hypothesis.stateful.RuleBasedStateMachine which asserts that an exception is raised under certain circumstances. pytest provides the raises context manager for writing tests about exceptions. If I use pytest.raises inside a…
jacg
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3
votes
2 answers
Sort dataframes generated by hypothesis when row tuples have different dtypes
I want to create dataframes where End is larger than Start.
This I do with:
from hypothesis.extra.pandas import columns, data_frames, column
import hypothesis.strategies as st
positions = st.integers(min_value=0, max_value=int(1e7))
strands =…
The Unfun Cat
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