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How to use run_block_program method in hypothesis

Best Python code snippet using hypothesis

shrinker.py

Source:shrinker.py

...1100            if can_replace_with(mid):1101                hi = mid1102            else:1103                lo = mid1104    def run_block_program(self, i, description, original, repeats=1):1105        """Block programs are a mini-DSL for block rewriting, defined as a sequence1106        of commands that can be run at some index into the blocks1107        Commands are:1108            * "-", subtract one from this block.1109            * "X", delete this block1110        If a command does not apply (currently only because it's - on a zero1111        block) the block will be silently skipped over.1112        This method runs the block program in ``description`` at block index1113        ``i`` on the ConjectureData ``original``. If ``repeats > 1`` then it1114        will attempt to approximate the results of running it that many times.1115        Returns True if this successfully changes the underlying shrink target,1116        else False.1117        """1118        if i + len(description) > len(original.blocks) or i < 0:1119            return False1120        attempt = bytearray(original.buffer)1121        for _ in range(repeats):1122            for k, d in reversed(list(enumerate(description))):1123                j = i + k1124                u, v = original.blocks[j].bounds1125                if v > len(attempt):1126                    return False1127                if d == "-":1128                    value = int_from_bytes(attempt[u:v])1129                    if value == 0:1130                        return False1131                    else:1132                        attempt[u:v] = int_to_bytes(value - 1, v - u)1133                elif d == "X":1134                    del attempt[u:v]1135                else:  # pragma: no cover1136                    raise AssertionError("Unrecognised command %r" % (d,))1137        return self.incorporate_new_buffer(attempt)1138def block_program(description):1139    """Mini-DSL for block rewriting. A sequence of commands that will be run1140    over all contiguous sequences of blocks of the description length in order.1141    Commands are:1142        * ".", keep this block unchanged1143        * "-", subtract one from this block.1144        * "0", replace this block with zero1145        * "X", delete this block1146    If a command does not apply (currently only because it's - on a zero1147    block) the block will be silently skipped over. As a side effect of1148    running a block program its score will be updated.1149    """1150    name = "block_program(%r)" % (description,)1151    if name not in SHRINK_PASS_DEFINITIONS:1152        """Defines a shrink pass that runs the block program ``description``1153        at every block index."""1154        n = len(description)1155        def run(self, chooser):1156            """Adaptively attempt to run the block program at the current1157            index. If this successfully applies the block program ``k`` times1158            then this runs in ``O(log(k))`` test function calls."""1159            i = chooser.choose(range(len(self.shrink_target.blocks) - n))1160            # First, run the block program at the chosen index. If this fails,1161            # don't do any extra work, so that failure is as cheap as possible.1162            if not self.run_block_program(i, description, original=self.shrink_target):1163                return1164            # Because we run in a random order we will often find ourselves in the middle1165            # of a region where we could run the block program. We thus start by moving1166            # left to the beginning of that region if possible in order to to start from1167            # the beginning of that region.1168            def offset_left(k):1169                return i - k * n1170            i = offset_left(1171                find_integer(1172                    lambda k: self.run_block_program(1173                        offset_left(k), description, original=self.shrink_target1174                    )1175                )1176            )1177            original = self.shrink_target1178            # Now try to run the block program multiple times here.1179            find_integer(1180                lambda k: self.run_block_program(1181                    i, description, original=original, repeats=k1182                )1183            )1184        run.__name__ = name1185        defines_shrink_pass()(run)1186        assert name in SHRINK_PASS_DEFINITIONS1187    return name1188@attr.s(slots=True, eq=False)1189class ShrinkPass:1190    run_with_chooser = attr.ib()1191    index = attr.ib()1192    shrinker = attr.ib()1193    next_prefix = attr.ib(default=())1194    fixed_point_at = attr.ib(default=None)...

test_conjecture_engine.py

Source:test_conjecture_engine.py

1# This file is part of Hypothesis, which may be found at2# https://github.com/HypothesisWorks/hypothesis/3#4# Most of this work is copyright (C) 2013-2020 David R. MacIver5# (david@drmaciver.com), but it contains contributions by others. See6# CONTRIBUTING.rst for a full list of people who may hold copyright, and7# consult the git log if you need to determine who owns an individual8# contribution.9#10# This Source Code Form is subject to the terms of the Mozilla Public License,11# v. 2.0. If a copy of the MPL was not distributed with this file, You can12# obtain one at https://mozilla.org/MPL/2.0/.13#14# END HEADER15from hypothesis import given, settings, strategies as st16from hypothesis.database import InMemoryExampleDatabase17from hypothesis.internal.compat import int_from_bytes18from hypothesis.internal.conjecture.data import ConjectureData19from hypothesis.internal.conjecture.engine import ConjectureRunner20from hypothesis.internal.conjecture.shrinker import Shrinker, block_program21from tests.common.utils import counts_calls, non_covering_examples22from tests.conjecture.common import run_to_buffer, shrinking_from23def test_lot_of_dead_nodes():24    @run_to_buffer25    def x(data):26        for i in range(4):27            if data.draw_bytes(1)[0] != i:28                data.mark_invalid()29        data.mark_interesting()30    assert x == bytes([0, 1, 2, 3])31def test_saves_data_while_shrinking(monkeypatch):32    key = b"hi there"33    n = 534    db = InMemoryExampleDatabase()35    assert list(db.fetch(key)) == []36    seen = set()37    monkeypatch.setattr(38        ConjectureRunner,39        "generate_new_examples",40        lambda runner: runner.cached_test_function([255] * 10),41    )42    def f(data):43        x = data.draw_bytes(10)44        if sum(x) >= 2000 and len(seen) < n:45            seen.add(x)46        if x in seen:47            data.mark_interesting()48    runner = ConjectureRunner(f, settings=settings(database=db), database_key=key)49    runner.run()50    assert runner.interesting_examples51    assert len(seen) == n52    in_db = non_covering_examples(db)53    assert in_db.issubset(seen)54    assert in_db == seen55def test_can_discard(monkeypatch):56    n = 857    monkeypatch.setattr(58        ConjectureRunner,59        "generate_new_examples",60        lambda runner: runner.cached_test_function(61            [v for i in range(n) for v in [i, i]]62        ),63    )64    @run_to_buffer65    def x(data):66        seen = set()67        while len(seen) < n:68            seen.add(bytes(data.draw_bytes(1)))69        data.mark_interesting()70    assert len(x) == n71def test_regression_1():72    # This is a really hard to reproduce bug that previously triggered a very73    # specific exception inside one of the shrink passes. It's unclear how74    # useful this regression test really is, but nothing else caught the75    # problem.76    @run_to_buffer77    def x(data):78        data.write(b"\x01\x02")79        data.write(b"\x01\x00")80        v = data.draw_bits(41)81        if v >= 512 or v == 254:82            data.mark_interesting()83    assert list(x)[:-2] == [1, 2, 1, 0, 0, 0, 0, 0]84    assert int_from_bytes(x[-2:]) in (254, 512)85@given(st.integers(0, 255), st.integers(0, 255))86def test_cached_with_masked_byte_agrees_with_results(byte_a, byte_b):87    def f(data):88        data.draw_bits(2)89    runner = ConjectureRunner(f)90    cached_a = runner.cached_test_function(bytes([byte_a]))91    cached_b = runner.cached_test_function(bytes([byte_b]))92    data_b = ConjectureData.for_buffer(93        bytes([byte_b]), observer=runner.tree.new_observer()94    )95    runner.test_function(data_b)96    # If the cache found an old result, then it should match the real result.97    # If it did not, then it must be because A and B were different.98    assert (cached_a is cached_b) == (cached_a.buffer == data_b.buffer)99def test_block_programs_fail_efficiently(monkeypatch):100    # Create 256 byte-sized blocks. None of the blocks can be deleted, and101    # every deletion attempt produces a different buffer.102    @shrinking_from(bytes(range(256)))103    def shrinker(data):104        values = set()105        for _ in range(256):106            v = data.draw_bits(8)107            values.add(v)108        if len(values) == 256:109            data.mark_interesting()110    monkeypatch.setattr(111        Shrinker, "run_block_program", counts_calls(Shrinker.run_block_program)112    )113    shrinker.max_stall = 500114    shrinker.fixate_shrink_passes([block_program("XX")])115    assert shrinker.shrinks == 0116    assert 250 <= shrinker.calls <= 260117    # The block program should have been run roughly 255 times, with a little118    # bit of wiggle room for implementation details.119    #   - Too many calls mean that failing steps are doing too much work.120    #   - Too few calls mean that this test is probably miscounting and buggy....

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