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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/.
import itertools
import math
from math import inf
import pytest
from hypothesis import (
HealthCheck,
assume,
example,
given,
note,
reject,
settings,
strategies as st,
)
from hypothesis.internal.conjecture.dfa import DEAD, ConcreteDFA
def test_enumeration_when_sizes_do_not_agree():
dfa = ConcreteDFA([{0: 1, 1: 2}, {}, {1: 3}, {}], {1, 3}) # 0 # 1 # 2 # 3
assert list(dfa.all_matching_strings()) == [b"\0", b"\1\1"]
def test_enumeration_of_very_long_strings():
"""This test is mainly testing that it terminates. If we were
to use a naive breadth first search for this it would take
forever to run because it would run in time roughly 256 ** 50.
"""
size = 50
dfa = ConcreteDFA(
[{c: n + 1 for c in range(256)} for n in range(100)] + [{}], {size}
)
for i, s in enumerate(dfa.all_matching_strings()):
assert len(s) == size
assert int.from_bytes(s, "big") == i
if i >= 1000:
break
def test_is_dead_with_cache_reuse():
dfa = ConcreteDFA([{0: i + 1, 1: 11} for i in range(10)] + [{}, {}], {10})
for n in range(10, -1, -1):
assert not dfa.is_dead(n)
def test_max_length_of_empty_dfa_is_zero():
dfa = ConcreteDFA([{}], {0})
assert dfa.max_length(dfa.start) == 0
def test_mixed_dfa_initialization():
d = ConcreteDFA([[(2, 1)], [(0, 5, 2)], {4: 0, 3: 1}], {0})
assert d.transition(0, 2) == 1
assert d.transition(0, 3) == DEAD
for n in range(6):
assert d.transition(1, n) == 2
assert d.transition(1, 6) == DEAD
assert d.transition(2, 4) == 0
assert d.transition(2, 3) == 1
assert d.transition(2, 5) == DEAD
@st.composite
def dfas(draw):
states = draw(st.integers(1, 20))
a_state = st.integers(0, states - 1)
a_byte = st.integers(0, 255)
start = draw(a_state)
accepting = draw(st.sets(a_state, min_size=1))
transitions = [draw(st.dictionaries(a_byte, a_state)) for _ in range(states)]
return ConcreteDFA(transitions, accepting, start)
@settings(max_examples=20)
@given(dfas(), st.booleans())
@example(
ConcreteDFA(
transitions=[[(0, 2), (1, 255, 1)], [(0, 2), (1, 255, 0)], []],
accepting={2},
),
False,
)
def test_canonicalised_matches_same_strings(dfa, via_repr):
canon = dfa.canonicalise()
note(canon)
if via_repr:
canon = eval(repr(canon))
assert dfa.max_length(dfa.start) == canon.max_length(canon.start)
try:
minimal = next(dfa.all_matching_strings())
except StopIteration:
reject()
assert minimal == next(canon.all_matching_strings())
assert dfa.count_strings(dfa.start, len(minimal)) == canon.count_strings(
canon.start, len(minimal)
)
# filters about 80% of examples. should potentially improve at some point.
@settings(max_examples=20, suppress_health_check=[HealthCheck.filter_too_much])
@given(dfas())
def test_has_string_of_max_length(dfa):
length = dfa.max_length(dfa.start)
assume(math.isfinite(length))
assume(not dfa.is_dead(dfa.start))
assert dfa.count_strings(dfa.start, length) > 0
def test_converts_long_tables_to_dicts():
dfa = ConcreteDFA(
[[(0, 0), (1, 1), (2, 2), (3, 1), (4, 0), (7, 10, 1)], [(0, 0)], []], {2}
)
assert dfa.transition(0, 2) == 2
assert dfa.transition(1, 0) == 0
assert isinstance(dfa._ConcreteDFA__transitions[0], dict)
assert isinstance(dfa._ConcreteDFA__transitions[1], list)
@settings(max_examples=20)
@given(dfas(), dfas())
def test_dfa_with_different_string_is_not_equivalent(x, y):
assume(not x.is_dead(x.start))
s = next(x.all_matching_strings())
assume(not y.matches(s))
assert not x.equivalent(y)
@example(x=b"", y=b"\0", z=b"\0")
@given(x=st.binary(), y=st.binary(min_size=1), z=st.binary())
def test_all_matching_regions_include_all_matches(x, y, z):
y_matcher = ConcreteDFA([{c: i + 1} for i, c in enumerate(y)] + [[]], {len(y)})
assert y_matcher.matches(y)
s = x + y + z
assert (len(x), len(x) + len(y)) in y_matcher.all_matching_regions(s)
@pytest.mark.parametrize("n", [1, 10, 100, 1000])
def test_max_length_of_long_dfa(n):
dfa = ConcreteDFA([{0: i + 1} for i in range(n)] + [{}], {n})
assert not dfa.is_dead(dfa.start)
assert dfa.max_length(dfa.start) == n
def test_dfa_with_cached_dead():
dfa = ConcreteDFA([[{0: 1, 1: 2}], [], []], {2})
assert dfa.is_dead(1)
assert dfa.is_dead(0)
@pytest.mark.parametrize("order", itertools.permutations((0, 1, 2)))
def test_dead_nodes(order):
dfa = ConcreteDFA([{0: 1, 1: 2}, {}, {}], {2})
for i in order:
assert dfa.is_dead(i) == (i == 1)
@given(st.permutations(range(5)))
def test_max_length_of_recursive_dfa(order):
dfa = ConcreteDFA([{0: 1, 1: 2, 2: 3}, {0: 2}, {0: 1}, {0: 0, 1: 4}, {}], {4})
for i in order:
dfa.max_length(i)
assert dfa.max_length(0) == inf
assert dfa.max_length(1) == 0
assert dfa.max_length(2) == 0
assert dfa.max_length(3) == inf
assert dfa.max_length(4) == 0
def test_transitions_out_of_dead_are_empty():
dfa = ConcreteDFA([{}], {0})
assert list(dfa.raw_transitions(DEAD)) == []
def test_can_transition_from_dead():
dfa = ConcreteDFA([{}], {0})
assert dfa.transition(DEAD, 0) == DEAD
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