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_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_example_source_needs_random():
with pytest.raises(ValueError):
ExampleSource(
random=None,
strategy=StrategyTable.default().strategy(int),
storage=None,
)
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_example_source_terminates_if_just_from_db():
db = ExampleDatabase()
storage = db.storage_for(int)
storage.save(1)
source = ExampleSource(random=random.Random(),
storage=storage,
strategy=None)
its = iter(source)
assert next(its) == 1
with pytest.raises(StopIteration):
next(its)
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_example_source_needs_at_least_one_useful_argument():
with pytest.raises(ValueError):
ExampleSource(random=random.Random(), storage=None, strategy=None)
def falsify(self, hypothesis, *argument_types): # pylint: disable=too-many-locals,too-many-branches
"""
Attempt to construct an example tuple x matching argument_types such
that hypothesis(*x) returns a falsey value or throws an AssertionError
"""
random = self.random
if random is None:
random = Random(function_digest(hypothesis))
search_strategy = (
self.strategy_table.specification_for(argument_types))
storage = None
if self.database is not None:
try:
storage = self.database.storage_for(argument_types)
except NotSerializeable:
pass
def falsifies(args): # pylint: disable=missing-docstring
try:
return not hypothesis(*search_strategy.copy(args))
except AssertionError:
return True
except UnsatisfiedAssumption:
return False
track_seen = Tracker()
falsifying_examples = []
examples_found = 0
satisfying_examples = 0
timed_out = False
if argument_types:
max_examples = self.max_examples
min_satisfying_examples = self.min_satisfying_examples
else:
max_examples = 1
min_satisfying_examples = 1
example_source = ExampleSource(random=random,
strategy=search_strategy,
storage=storage,
min_parameters=max(
2, int(float(max_examples) / 10)))
start_time = time.time()
def time_to_call_it_a_day():
"""Have we exceeded our timeout?"""
return time.time() >= start_time + self.timeout
skipped_examples = 0
examples_seen = 0
# At present this loop will never exit normally . This needs proper
# testing when "database only" mode becomes available but right now
# it's not.
for args in example_source: # pragma: no branch
assert search_strategy.could_have_produced(args)
if falsifying_examples:
break
if examples_seen >= max_examples:
break
if time_to_call_it_a_day():
break
examples_seen += 1
if track_seen.track(args) > 1:
example_source.mark_bad()
skipped_examples += 1
if skipped_examples >= self.max_skipped_examples:
raise Exhausted(hypothesis, examples_found)
else:
# This really is covered. I suspect a bug in coverage that
# I have not yet narrowed down. It is impossible to execute
# the other branch without first executing this one and
# there is a test that cannot pass without executing the
# other branch.
continue # pragma: no cover
else:
skipped_examples = 0
examples_found += 1
try:
is_falsifying_example = not hypothesis(
*search_strategy.copy(args))
except AssertionError:
is_falsifying_example = True
except UnsatisfiedAssumption:
example_source.mark_bad()
continue
satisfying_examples += 1
if is_falsifying_example:
falsifying_examples.append(args)
run_time = time.time() - start_time
timed_out = run_time >= self.timeout
if not falsifying_examples:
if satisfying_examples < min_satisfying_examples:
raise Unsatisfiable(hypothesis, satisfying_examples, run_time)
elif timed_out:
raise Timeout(hypothesis, satisfying_examples, run_time)
else:
raise Unfalsifiable(hypothesis)
for example in falsifying_examples:
if not falsifies(example):
raise Flaky(hypothesis, example)
best_example = falsifying_examples[0]
for simpler in search_strategy.simplify_such_that(
best_example, falsifies):
best_example = simpler
if time_to_call_it_a_day():
break
if storage is not None:
storage.save(best_example)
return best_example
