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bemaniutils/bemani/tests/test_lz77.py

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# vim: set fileencoding=utf-8
import os
import random
import unittest
from bemani.protocol.lz77 import Lz77, Lz77Decompress
from bemani.tests.helpers import get_fixture
class TestLZ77Decompressor(unittest.TestCase):
def test_ringbuffer_fuzz(self) -> None:
dec = Lz77Decompress(b"")
for _ in range(100):
amount = random.randint(1, Lz77Decompress.RING_LENGTH)
data = os.urandom(amount)
# Save our ring position, write a chunk of data
readpos = dec.write_pos
dec._ring_write(data)
# Read a chunk of data back from that buffer, see its the same
newdata = b"".join(dec._ring_read(readpos, amount))
self.assertEqual(data, newdata)
# Verify integrity of ringbuffer
self.assertEqual(len(dec.ring), Lz77Decompress.RING_LENGTH)
class TestLz77RealCompressor(unittest.TestCase):
def test_small_data_random(self) -> None:
lz77 = Lz77()
data = os.urandom(1 * 1024)
compresseddata = lz77.compress(data)
self.assertNotEqual(data, compresseddata)
decompresseddata = lz77.decompress(compresseddata)
self.assertEqual(data, decompresseddata)
def test_large_data_random(self) -> None:
lz77 = Lz77()
data = os.urandom(100 * 1024)
compresseddata = lz77.compress(data)
self.assertNotEqual(data, compresseddata)
decompresseddata = lz77.decompress(compresseddata)
self.assertEqual(data, decompresseddata)
def test_huge_data_random(self) -> None:
lz77 = Lz77()
data = os.urandom(1 * 1024 * 1024)
compresseddata = lz77.compress(data)
self.assertNotEqual(data, compresseddata)
decompresseddata = lz77.decompress(compresseddata)
self.assertEqual(data, decompresseddata)
def test_declaration(self) -> None:
lz77 = Lz77()
data = get_fixture("declaration.txt")
compresseddata = lz77.compress(data)
self.assertNotEqual(data, compresseddata)
self.assertTrue(len(compresseddata) < len(data))
decompresseddata = lz77.decompress(compresseddata)
self.assertEqual(data, decompresseddata)
def test_lorem_ipsum(self) -> None:
lz77 = Lz77()
data = get_fixture("lorem.txt")
compresseddata = lz77.compress(data)
self.assertNotEqual(data, compresseddata)
self.assertTrue(len(compresseddata) < len(data))
decompresseddata = lz77.decompress(compresseddata)
self.assertEqual(data, decompresseddata)
def test_texture(self) -> None:
lz77 = Lz77()
data = get_fixture("rawdata")
compresseddata = lz77.compress(data)
self.assertNotEqual(data, compresseddata)
self.assertTrue(len(compresseddata) < len(data))
decompresseddata = lz77.decompress(compresseddata)
self.assertEqual(data, decompresseddata)
def test_known_compression(self) -> None:
"""
Specifically tests for ability to compress an overlap,
verifies that we don't regress on known compressions.
"""
lz77 = Lz77()
data = b"abcabcabcabc"
compresseddata = lz77.compress(data)
self.assertEqual(b"\x07abc\x006\x00\x00", compresseddata)
decompresseddata = lz77.decompress(compresseddata)
self.assertEqual(data, decompresseddata)