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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 hypothesis import given, settings, strategies as st
from hypothesis.database import InMemoryExampleDatabase
from hypothesis.internal.compat import int_from_bytes
from hypothesis.internal.conjecture.data import ConjectureData
from hypothesis.internal.conjecture.engine import ConjectureRunner
from hypothesis.internal.conjecture.shrinker import Shrinker, block_program
from tests.common.utils import counts_calls, non_covering_examples
from tests.conjecture.common import run_to_buffer, shrinking_from
def test_lot_of_dead_nodes():
@run_to_buffer
def x(data):
for i in range(4):
if data.draw_bytes(1)[0] != i:
data.mark_invalid()
data.mark_interesting()
assert x == bytes([0, 1, 2, 3])
def test_saves_data_while_shrinking(monkeypatch):
key = b"hi there"
n = 5
db = InMemoryExampleDatabase()
assert list(db.fetch(key)) == []
seen = set()
monkeypatch.setattr(
ConjectureRunner,
"generate_new_examples",
lambda runner: runner.cached_test_function([255] * 10),
)
def f(data):
x = data.draw_bytes(10)
if sum(x) >= 2000 and len(seen) < n:
seen.add(x)
if x in seen:
data.mark_interesting()
runner = ConjectureRunner(f, settings=settings(database=db), database_key=key)
runner.run()
assert runner.interesting_examples
assert len(seen) == n
in_db = non_covering_examples(db)
assert in_db.issubset(seen)
assert in_db == seen
def test_can_discard(monkeypatch):
n = 8
monkeypatch.setattr(
ConjectureRunner,
"generate_new_examples",
lambda runner: runner.cached_test_function(
[v for i in range(n) for v in [i, i]]
),
)
@run_to_buffer
def x(data):
seen = set()
while len(seen) < n:
seen.add(bytes(data.draw_bytes(1)))
data.mark_interesting()
assert len(x) == n
def test_regression_1():
# This is a really hard to reproduce bug that previously triggered a very
# specific exception inside one of the shrink passes. It's unclear how
# useful this regression test really is, but nothing else caught the
# problem.
@run_to_buffer
def x(data):
data.write(b"\x01\x02")
data.write(b"\x01\x00")
v = data.draw_bits(41)
if v >= 512 or v == 254:
data.mark_interesting()
assert list(x)[:-2] == [1, 2, 1, 0, 0, 0, 0, 0]
assert int_from_bytes(x[-2:]) in (254, 512)
@given(st.integers(0, 255), st.integers(0, 255))
def test_cached_with_masked_byte_agrees_with_results(byte_a, byte_b):
def f(data):
data.draw_bits(2)
runner = ConjectureRunner(f)
cached_a = runner.cached_test_function(bytes([byte_a]))
cached_b = runner.cached_test_function(bytes([byte_b]))
data_b = ConjectureData.for_buffer(
bytes([byte_b]), observer=runner.tree.new_observer()
)
runner.test_function(data_b)
# If the cache found an old result, then it should match the real result.
# If it did not, then it must be because A and B were different.
assert (cached_a is cached_b) == (cached_a.buffer == data_b.buffer)
def test_block_programs_fail_efficiently(monkeypatch):
# Create 256 byte-sized blocks. None of the blocks can be deleted, and
# every deletion attempt produces a different buffer.
@shrinking_from(bytes(range(256)))
def shrinker(data):
values = set()
for _ in range(256):
v = data.draw_bits(8)
values.add(v)
if len(values) == 256:
data.mark_interesting()
monkeypatch.setattr(
Shrinker, "run_block_program", counts_calls(Shrinker.run_block_program)
)
shrinker.max_stall = 500
shrinker.fixate_shrink_passes([block_program("XX")])
assert shrinker.shrinks == 0
assert 250 <= shrinker.calls <= 260
# The block program should have been run roughly 255 times, with a little
# bit of wiggle room for implementation details.
# - Too many calls mean that failing steps are doing too much work.
# - Too few calls mean that this test is probably miscounting and buggy.
assert 250 <= Shrinker.run_block_program.calls <= 260
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