def test_shrinker_skips_stale_examples(monkeypatch, pass_name):
# Pretend that all example identifiers are stale, to test that this case
# is handled cleanly.
monkeypatch.setattr(
Shrinker, "example_for_stable_identifier", counts_calls(lambda self, x: None)
)
# For "example_deletion_with_block_lowering", also pretend that all blocks
# are shrinking blocks, so that steps can be generated.
monkeypatch.setattr(
Shrinker, "is_shrinking_block", counts_calls(lambda self, i: True)
)
# Declare a test function that should satisfy step generation for all of
# the relevant shrink passes.
@shrinking_from([255] * 5)
def shrinker(data):
total = 0
data.start_example(0)
for _ in range(5):
data.start_example(0)
total += data.draw_bits(8)
data.stop_example(0)
data.stop_example(0)
data.mark_interesting()
# Run the shrink pass; this should not throw.
shrinker.fixate_shrink_passes([pass_name])
# Confirm that the pass had to deal with stale examples.
assert Shrinker.example_for_stable_identifier.calls > 0
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
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(hbytes(hrange(256)))
def shrinker(data):
values = set()
for _ in hrange(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.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