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# 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/.
from random import Random
from hypothesis import given, strategies as st
from hypothesis.internal.conjecture.shrinking.choicetree import (
ChoiceTree,
prefix_selection_order,
random_selection_order,
)
def select(*args):
return prefix_selection_order(args)
def exhaust(f):
tree = ChoiceTree()
results = []
prefix = ()
while not tree.exhausted:
prefix = tree.step(
prefix_selection_order(prefix), lambda chooser: results.append(f(chooser))
)
return results
@given(st.lists(st.integers()))
def test_can_enumerate_a_shallow_set(ls):
results = exhaust(lambda chooser: chooser.choose(ls))
assert sorted(results) == sorted(ls)
def test_can_enumerate_a_nested_set():
@exhaust
def nested(chooser):
i = chooser.choose(range(10))
j = chooser.choose(range(10), condition=lambda j: j > i)
return (i, j)
assert sorted(nested) == [(i, j) for i in range(10) for j in range(i + 1, 10)]
def test_can_enumerate_empty():
@exhaust
def empty(chooser):
return 1
assert empty == [1]
def test_all_filtered_child():
@exhaust
def all_filtered(chooser):
chooser.choose(range(10), condition=lambda j: False)
assert all_filtered == []
def test_skips_over_exhausted_children():
results = []
def f(chooser):
results.append(
(
chooser.choose(range(3), condition=lambda x: x > 0),
chooser.choose(range(2)),
)
)
tree = ChoiceTree()
tree.step(select(1, 0), f)
tree.step(select(1, 1), f)
tree.step(select(0, 0), f)
assert results == [(1, 0), (1, 1), (2, 0)]
def test_extends_prefix_from_right():
def f(chooser):
chooser.choose(range(4))
tree = ChoiceTree()
result = tree.step(select(), f)
assert result == (3,)
def test_starts_from_the_end():
def f(chooser):
chooser.choose(range(3))
tree = ChoiceTree()
assert tree.step(select(), f) == (2,)
def test_skips_over_exhausted_subtree():
def f(chooser):
chooser.choose(range(10))
tree = ChoiceTree()
assert tree.step(select(8), f) == (8,)
assert tree.step(select(8), f) == (7,)
def test_exhausts_randomly():
def f(chooser):
chooser.choose(range(10))
tree = ChoiceTree()
random = Random()
seen = set()
for _ in range(10):
seen.add(tree.step(random_selection_order(random), f))
assert len(seen) == 10
assert tree.exhausted
def test_exhausts_randomly_when_filtering():
def f(chooser):
chooser.choose(range(10), lambda x: False)
tree = ChoiceTree()
random = Random()
tree.step(random_selection_order(random), f)
assert tree.exhausted
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