def test_can_simplify_leap_years():
s = StrategyTable().strategy(datetime)
d = datetime(year=2012, month=2, day=29)
t = list(
s.simplify_such_that(
d, lambda x:
(x.month == 2) and (x.day == 29) and (x.year > 2000)))[-1]
assert t.year == 2004
def test_a_derandomized_verifier_produces_the_same_results_called_twice():
table = StrategyTable()
settings = hs.Settings(derandomize=True)
table.define_specification_for(float, lambda *_: BrokenFloatStrategy())
v1 = Verifier(strategy_table=table, settings=settings)
foo = lambda x: False
x1 = v1.falsify(foo, float)
x2 = v1.falsify(foo, float)
assert x1 == x2
def test_minor_variations_in_code_change_the_randomization():
table = StrategyTable()
settings = hs.Settings(derandomize=True)
settings.database = None
table.define_specification_for(float, lambda *_: BrokenFloatStrategy())
v1 = Verifier(strategy_table=table, settings=settings)
x1 = v1.falsify(lambda x: x == 42, float)
x2 = v1.falsify(lambda x: x == 1, float)
assert x1 != x2
def test_two_verifiers_produce_different_results_in_normal_mode():
settings = hs.Settings()
settings.database = None
table = StrategyTable()
table.define_specification_for(float, lambda *_: BrokenFloatStrategy())
v1 = Verifier(strategy_table=table, settings=settings)
v2 = Verifier(strategy_table=table, settings=settings)
x1 = v1.falsify(lambda x: False, float)
x2 = v2.falsify(lambda x: False, float)
assert x1 != x2
def __init__(
self,
strategy_table=None,
random=None,
settings=None,
):
if settings is None:
settings = hs.default
self.database = settings.database
self.strategy_table = strategy_table or StrategyTable()
if self.database is not None:
self.strategy_table = self.strategy_table.augment_with_examples(
self.examples_for
)
self.min_satisfying_examples = settings.min_satisfying_examples
self.max_skipped_examples = settings.max_skipped_examples
self.max_examples = settings.max_examples
self.timeout = settings.timeout
if settings.derandomize and random:
raise ValueError(
'A verifier cannot both be derandomized and have a random '
'generator')
if settings.derandomize:
self.random = None
else:
self.random = random or Random()
self.max_regenerations = 0
def test_example_source_needs_random():
with pytest.raises(ValueError):
ExampleSource(
random=None,
strategy=StrategyTable.default().strategy(int),
storage=None,
)
def test_can_grow_the_set_of_available_parameters_if_doing_badly():
runs = 10
number_grown = 0
number_grown_large = 0
for _ in hrange(runs):
source = ExampleSource(
random=random.Random(),
strategy=StrategyTable.default().strategy(int),
storage=None,
min_parameters=1,
)
i = 0
for example in source:
if example < 0:
source.mark_bad()
i += 1
if i >= 100:
break
if len(source.parameters) > 1:
number_grown += 1
if len(source.parameters) > 10:
number_grown_large += 1
assert number_grown >= 0.5 * runs
assert number_grown_large <= 0.5 * runs
def test_errors_if_you_mark_bad_before_fetching():
storage = None
if hs.default.database is not None:
storage = hs.default.database.storage_for(int)
source = ExampleSource(
random=random.Random(),
strategy=StrategyTable.default().strategy(int),
storage=storage,
)
with pytest.raises(ValueError):
source.mark_bad()
def test_storage_does_not_return_things_not_matching_strategy():
table = StrategyTable()
strategy = JustStrategy(PickyStrategyLazyFormat())
strategy.could_have_produced = lambda *args: False
table.define_specification_for(PickyStrategyLazyFormat,
lambda s, d: strategy)
converters = ConverterTable(strategy_table=table)
converters.define_specification_for(
PickyStrategyLazyFormat,
lambda s, d: JustConverter(PickyStrategyLazyFormat()))
database = ExampleDatabase(
converters=converters,
backend=SQLiteBackend(),
)
stor = database.storage_for(PickyStrategyLazyFormat)
database.backend.save(stor.key, 'null')
assert list(database.backend.fetch(stor.key)) != []
assert list(stor.fetch()) == []
assert list(database.backend.fetch(stor.key)) == []
def test_tries_each_parameter_at_least_min_index_times():
source = ExampleSource(random=random.Random(),
strategy=StrategyTable.default().strategy(int),
storage=None,
min_tries=5)
i = 0
for x in source:
i += 1
if i > 500:
break
if i % 2:
source.mark_bad()
# The last index may not have been fully populated
assert all(c >= 5 for c in source.counts[:-1])
def test_negative_is_not_too_far_off_mean():
source = ExampleSource(
random=random.Random(),
strategy=StrategyTable.default().strategy(int),
storage=None,
)
positive = 0
i = 0
for example in source:
if example >= 0:
positive += 1
i += 1
if i >= N_EXAMPLES:
break
assert 0.3 <= float(positive) / N_EXAMPLES <= 0.7
def test_marking_negative_avoids_similar_examples():
source = ExampleSource(
random=random.Random(),
strategy=StrategyTable.default().strategy(int),
storage=None,
)
positive = 0
i = 0
for example in source:
if example >= 0:
positive += 1
else:
source.mark_bad()
i += 1
if i >= N_EXAMPLES:
break
assert float(positive) / N_EXAMPLES >= 0.8
def test_can_falsify_types_without_default_productions():
strategies = StrategyTable()
strategies.define_specification_for(
Bar, lambda s, d: BarStrategy(
s.strategy(descriptors.integers_in_range(0, 100))))
with pytest.raises(MissingSpecification):
StrategyTable.default().strategy(Bar)
verifier = Verifier(strategy_table=strategies)
assert verifier.falsify(
lambda x: False,
Bar,
)[0] == Bar()
assert verifier.falsify(lambda x: x.size() < 3, Bar)[0] == Bar(Bar(Bar()))
def run_test():
if condition is None:
_condition = lambda x: True
condition_string = ''
else:
_condition = condition
condition_string = strip_lambda(
reflection.get_pretty_function_description(condition))
count = 0
successful_runs = 0
strategy = StrategyTable.default().strategy(descriptor)
for _ in hrange(MAX_RUNS):
pv = strategy.parameter.draw(random)
x = strategy.produce(random, pv)
if not _condition(x):
continue
successful_runs += 1
if predicate(x):
count += 1
if successful_runs < MIN_RUNS:
raise ConditionTooHard(
('Unable to find enough examples satisfying predicate %s '
'only found %d but required at least %d for validity') %
(condition_string, successful_runs, MIN_RUNS))
result = Result(
count,
successful_runs,
q,
predicate,
condition_string,
)
p = cumulative_binomial_probability(successful_runs, q, count)
run_test.test_result = result
# The test passes if we fail to reject the null hypothesis that
# the probability is at least q
if p < REQUIRED_P:
result.failed = True
raise HypothesisFalsified(result.description() + ' rejected')
def test_can_derandomize_on_evalled_functions():
table = StrategyTable()
settings = hs.Settings(derandomize=True)
v = Verifier(strategy_table=table, settings=settings)
assert v.falsify(eval('lambda x: x > 0'), int) == (0, )
from hypothesis import Verifier
import hypothesis.settings as hs
from hypothesis.strategytable import StrategyTable
import hypothesis.searchstrategy as strat
settings = hs.Settings(max_examples=100, timeout=4)
small_table = StrategyTable()
small_table.define_specification_for_instances(
list,
lambda strategies, descriptor:
strat.ListStrategy(
list(map(strategies.strategy, descriptor)),
average_length=2.0
)
)
small_verifier = Verifier(
settings=settings,
strategy_table=small_table,
)
def test_minimizes_to_empty(desc):
x = falsify(always_false, desc)[0]
s = StrategyTable.default().strategy(desc)
assert not list(s.simplify(x))
def __init__(self, strategy_table=None):
super(ConverterTable, self).__init__()
self.strategy_table = strategy_table or StrategyTable.default()
steps=steps,
init_args=init_args,
init_kwargs=init_kwargs
)
return TestRun(self.descriptor, steps)
def unpack(self, x):
steps = x.steps
if self.requires_init:
return ((x.init_args, x.init_kwargs), steps)
else:
return steps
def simplify(self, x):
pruned = x.prune()
if pruned:
yield pruned
for y in super(StatefulStrategy, self).simplify(x):
yield y
StrategyTable.default().define_specification_for_classes(
define_stateful_strategy,
subclasses_of=StatefulTest
)
ConverterTable.default().define_specification_for_classes(
StatefulConverter,
subclasses_of=StatefulTest
)
def load():
StrategyTable.default().define_specification_for(
datetime, lambda s, d: DatetimeStrategy())
class Awkward(str):
pass
ConverterTable.default().mark_not_serializeable(Awkward)
class AwkwardStrategy(SearchStrategy):
descriptor = Awkward
parameter = params.CompositeParameter()
def produce(self, random, pv):
return Awkward()
StrategyTable.default().define_specification_for(
Awkward, lambda s, d: AwkwardStrategy())
def test_can_verify_a_non_serializale_type():
verifier = Verifier(settings=hs.Settings(database=ExampleDatabase()))
verifier.falsify(lambda x: len(x) > 0, Awkward)
def test_verifier_deduplicates_on_coming_out_of_the_database():
db = ExampleDatabase()
storage = db.storage_for((frozenset({int}), ))
db.backend.save(storage.key, '[1, 2, 3]')
db.backend.save(storage.key, '[3, 2, 1]')
counter = Counter()
calls = []
good = frozenset({1, 2, 3})
