# This file is part of Hypothesis, which may be found at
# Most of this work is copyright (C) 2013-2018 David R. MacIver
# (email@example.com), but it contains contributions by others. See
# CONTRIBUTING.rst for a full list of people who may hold copyright, and
# consult the git log if you need to determine who owns an individual
# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at http://mozilla.org/MPL/2.0/.
# END HEADER
from __future__ import absolute_import, division, print_function
"""Generic parent class for exceptions thrown by Hypothesis."""
"""At least one cleanup task failed and no other exception was raised."""
"""An internal error raised by assume.
If you're seeing this error something has gone wrong.
"""An internal error raised when something unfortunate happened during
template generation and you should restart the draw, preferably with a new
This is not an error condition internally, but if you ever see this
in your code it's probably a Hypothesis bug
"""The condition we have been asked to satisfy appears to be always false.
This does not guarantee that no example exists, only that we were
unable to find one.
def __init__(self, condition_string, extra=""):
"No examples found of condition %s%s" % (condition_string, extra)
class DefinitelyNoSuchExample(NoSuchExample): # pragma: no cover
"""Hypothesis used to be able to detect exhaustive coverage of a search
space and no longer can.
This exception remains for compatibility reasons for now but can
never actually be thrown.
"""Raised when example() is called on a strategy but we cannot find any
examples after enough tries that we really should have been able to if this
was ever going to work."""
"""We ran out of time or examples before we could find enough examples
which satisfy the assumptions of this hypothesis.
This could be because the function is too slow. If so, try upping
the timeout. It could also be because the function is using assume
in a way that is too hard to satisfy. If so, try writing a custom
strategy or using a better starting point (e.g if you are requiring
a list has unique values you could instead filter out all duplicate
values from the list)
"""This function appears to fail non-deterministically: We have seen it
fail when passed this example at least once, but a subsequent invocation
did not fail.
Common causes for this problem are:
1. The function depends on external state. e.g. it uses an external
random number generator. Try to make a version that passes all the
relevant state in from Hypothesis.
2. The function is suffering from too much recursion and its failure
depends sensitively on where it's been called from.
3. The function is timing sensitive and can fail or pass depending on
how long it takes. Try breaking it up into smaller functions which
don't do that and testing those instead.
"""We were unable to find enough examples that satisfied the preconditions
of this hypothesis in the amount of time allotted to us."""
class WrongFormat(HypothesisException, ValueError):
"""An exception indicating you have attempted to serialize a value that
does not match the type described by this format."""
class BadData(HypothesisException, ValueError):
"""The data that we got out of the database does not seem to match the data
we could have put into the database given this schema."""
class InvalidArgument(HypothesisException, TypeError):
"""Used to indicate that the arguments to a Hypothesis function were in
some manner incorrect."""
"""Hypothesis had to resolve a type to a strategy, but this failed.
Type inference is best-effort, so this only happens when an
annotation exists but could not be resolved for a required argument
to the target of ``builds()``, or where the user passed ``infer``.
"""The system is not in a state where you were allowed to do that."""
class InvalidDefinition(HypothesisException, TypeError):
"""Used to indicate that a class definition was not well put together and
has something wrong with it."""
"""Raised when a test running in a child process exits without returning or
raising an exception."""
class FailedHealthCheck(HypothesisException, Warning):
"""Raised when a test fails a preliminary healthcheck that occurs before
def __init__(self, message, check):
self.health_check = check
class HypothesisWarning(HypothesisException, Warning):
"""A generic warning issued by Hypothesis."""
[docs]class HypothesisDeprecationWarning(HypothesisWarning, FutureWarning):
"""A deprecation warning issued by Hypothesis.
Actually inherits from FutureWarning, because DeprecationWarning is
hidden by the default warnings filter.
You can configure the Python :mod:`python:warnings` to handle these
warnings differently to others, either turning them into errors or
suppressing them entirely. Obviously we would prefer the former!
"""Raised when a mutation method has been called on a ConjectureData object
after freeze() has been called."""
"""Indicates that Hypothesis found more than one distinct bug when testing
"""Raised when an individual test body has taken too long to run."""
def __init__(self, runtime, deadline):
("Test took %.2fms, which exceeds the deadline of " "%.2fms")
% (runtime, deadline)
self.runtime = runtime
self.deadline = deadline
def __init__(self, testcounter):
self.testcounter = testcounter