test_float_shrinking.py

# This file is part of Hypothesis, which may be found at
# https://github.com/HypothesisWorks/hypothesis/
#
# Most of this work is copyright (C) 2013-2020 David R. MacIver
# (david@drmaciver.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
# contribution.
#
# 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 https://mozilla.org/MPL/2.0/.
#
# END HEADER

import pytest

from hypothesis import (
    HealthCheck,
    Verbosity,
    assume,
    example,
    given,
    settings,
    strategies as st,
)
from hypothesis.internal.compat import ceil
from tests.common.debug import minimal


def test_shrinks_to_simple_floats():
    assert minimal(st.floats(), lambda x: x > 1) == 2.0
    assert minimal(st.floats(), lambda x: x > 0) == 1.0


@pytest.mark.parametrize("n", [1, 2, 3, 8, 10])
def test_can_shrink_in_variable_sized_context(n):
    x = minimal(st.lists(st.floats(), min_size=n), any)
    assert len(x) == n
    assert x.count(0.0) == n - 1
    assert 1 in x


@example(1.7976931348623157e308)
@example(1.5)
@given(st.floats(min_value=0, allow_infinity=False, allow_nan=False))
@settings(deadline=None, suppress_health_check=HealthCheck.all())
def test_shrinks_downwards_to_integers(f):
    g = minimal(st.floats(), lambda x: x >= f, settings(verbosity=Verbosity.quiet))
    assert g == ceil(f)


@example(1)
@given(st.integers(1, 2 ** 16 - 1))
@settings(deadline=None, suppress_health_check=HealthCheck.all(), max_examples=10)
def test_shrinks_downwards_to_integers_when_fractional(b):
    g = minimal(
        st.floats(),
        lambda x: assume((0 < x < (2 ** 53)) and int(x) != x) and x >= b,
        settings=settings(verbosity=Verbosity.quiet, max_examples=10 ** 6),
    )
    assert g == b + 0.5