test_core.py

# This file is part of Hypothesis, which may be found at
# https://github.com/HypothesisWorks/hypothesis/
#
# Copyright the Hypothesis Authors.
# Individual contributors are listed in AUTHORS.rst and the git log.
#
# 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/.

import unittest

import pytest
from _pytest.outcomes import Failed, Skipped

from hypothesis import Phase, example, find, given, reject, settings, strategies as s
from hypothesis.database import InMemoryExampleDatabase
from hypothesis.errors import InvalidArgument, NoSuchExample, Unsatisfiable


def test_stops_after_max_examples_if_satisfying():
    tracker = []

    def track(x):
        tracker.append(x)
        return False

    max_examples = 100

    with pytest.raises(NoSuchExample):
        find(s.integers(0, 10000), track, settings=settings(max_examples=max_examples))

    assert len(tracker) == max_examples


def test_stops_after_ten_times_max_examples_if_not_satisfying():
    count = [0]

    def track(x):
        count[0] += 1
        reject()

    max_examples = 100

    with pytest.raises(Unsatisfiable):
        find(s.integers(0, 10000), track, settings=settings(max_examples=max_examples))

    # Very occasionally we can generate overflows in generation, which also
    # count towards our example budget, which means that we don't hit the
    # maximum.
    assert count[0] <= 10 * max_examples


some_normal_settings = settings()


def test_is_not_normally_default():
    assert settings.default is not some_normal_settings


@given(s.booleans())
@some_normal_settings
def test_settings_are_default_in_given(x):
    assert settings.default is some_normal_settings


def test_given_shrinks_pytest_helper_errors():
    final_value = [None]

    @settings(derandomize=True, max_examples=100)
    @given(s.integers())
    def inner(x):
        final_value[0] = x
        if x > 100:
            pytest.fail(f"x={x!r} is too big!")

    with pytest.raises(Failed):
        inner()
    assert final_value[0] == 101


def test_pytest_skip_skips_shrinking():
    values = []

    @settings(derandomize=True, max_examples=100)
    @given(s.integers())
    def inner(x):
        values.append(x)
        if x > 100:
            pytest.skip(f"x={x!r} is too big!")

    with pytest.raises(Skipped):
        inner()
    assert len([x for x in values if x > 100]) == 1


def test_can_find_with_db_eq_none():
    find(s.integers(), bool, settings=settings(database=None, max_examples=100))


def test_no_such_example():
    with pytest.raises(NoSuchExample):
        find(s.none(), bool, database_key=b"no such example")


def test_validates_strategies_for_test_method():
    invalid_strategy = s.lists(s.nothing(), min_size=1)

    class TestStrategyValidation:
        @given(invalid_strategy)
        def test_method_with_bad_strategy(self, x):
            pass

    instance = TestStrategyValidation()
    with pytest.raises(InvalidArgument):
        instance.test_method_with_bad_strategy()


@example(1)
@given(s.integers())
@settings(phases=[Phase.target, Phase.shrink, Phase.explain])
def no_phases(_):
    raise Exception


@given(s.integers())
@settings(phases=[Phase.explicit])
def no_explicit(_):
    raise Exception


@given(s.integers())
@settings(phases=[Phase.reuse], database=InMemoryExampleDatabase())
def empty_db(_):
    raise Exception


@pytest.mark.parametrize(
    "test_fn",
    [no_phases, no_explicit, empty_db],
    ids=lambda t: t.__name__,
)
def test_non_executed_tests_raise_skipped(test_fn):
    with pytest.raises(unittest.SkipTest):
        test_fn()