File: test_collective_minimization.py

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# coding=utf-8
#
# This file is part of Hypothesis, which may be found at
# https://github.com/HypothesisWorks/hypothesis-python
#
# Most of this work is copyright (C) 2013-2016 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 http://mozilla.org/MPL/2.0/.
#
# END HEADER

from __future__ import division, print_function, absolute_import

import pytest
from flaky import flaky

from hypothesis import find, settings
from tests.common import standard_types
from hypothesis.errors import NoSuchExample
from hypothesis.strategies import lists


@pytest.mark.parametrize(
    u'spec', standard_types, ids=list(map(repr, standard_types)))
@flaky(min_passes=1, max_runs=2)
def test_can_collectively_minimize(spec):
    """This should generally exercise strategies' strictly_simpler heuristic by
    putting us in a state where example cloning is required to get to the
    answer fast enough."""
    n = 10

    def distinct_reprs(x):
        result = set()
        for t in x:
            result.add(repr(t))
            if len(result) >= 2:
                return True
        return False

    try:
        xs = find(
            lists(spec, min_size=n, max_size=n),
            distinct_reprs,
            settings=settings(
                timeout=10.0, max_examples=2000))
        assert len(xs) == n
        assert 2 <= len(set((map(repr, xs)))) <= 3
    except NoSuchExample:
        pass