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import io
import struct
import unittest
import zstandard as zstd
class TestCompressor_compressobj(unittest.TestCase):
def test_compressobj_empty(self):
cctx = zstd.ZstdCompressor(level=1, write_content_size=False)
cobj = cctx.compressobj()
self.assertEqual(cobj.compress(b""), b"")
self.assertEqual(cobj.flush(), b"\x28\xb5\x2f\xfd\x00\x00\x01\x00\x00")
def test_input_types(self):
expected = b"\x28\xb5\x2f\xfd\x00\x48\x19\x00\x00\x66\x6f\x6f"
cctx = zstd.ZstdCompressor(level=1, write_content_size=False)
mutable_array = bytearray(3)
mutable_array[:] = b"foo"
sources = [
memoryview(b"foo"),
bytearray(b"foo"),
mutable_array,
]
for source in sources:
cobj = cctx.compressobj()
self.assertEqual(cobj.compress(source), b"")
self.assertEqual(cobj.flush(), expected)
def test_compressobj_large(self):
chunks = []
for i in range(255):
chunks.append(struct.Struct(">B").pack(i) * 16384)
cctx = zstd.ZstdCompressor(level=3)
cobj = cctx.compressobj()
result = cobj.compress(b"".join(chunks)) + cobj.flush()
self.assertEqual(len(result), 1029)
self.assertEqual(result[0:4], b"\x28\xb5\x2f\xfd")
params = zstd.get_frame_parameters(result)
self.assertEqual(params.content_size, zstd.CONTENTSIZE_UNKNOWN)
self.assertEqual(params.window_size, 2097152)
self.assertEqual(params.dict_id, 0)
self.assertFalse(params.has_checksum)
def test_write_checksum(self):
cctx = zstd.ZstdCompressor(level=1)
cobj = cctx.compressobj()
no_checksum = cobj.compress(b"foobar") + cobj.flush()
cctx = zstd.ZstdCompressor(level=1, write_checksum=True)
cobj = cctx.compressobj()
with_checksum = cobj.compress(b"foobar") + cobj.flush()
no_params = zstd.get_frame_parameters(no_checksum)
with_params = zstd.get_frame_parameters(with_checksum)
self.assertEqual(no_params.content_size, zstd.CONTENTSIZE_UNKNOWN)
self.assertEqual(with_params.content_size, zstd.CONTENTSIZE_UNKNOWN)
self.assertEqual(no_params.dict_id, 0)
self.assertEqual(with_params.dict_id, 0)
self.assertFalse(no_params.has_checksum)
self.assertTrue(with_params.has_checksum)
self.assertEqual(len(with_checksum), len(no_checksum) + 4)
def test_write_content_size(self):
cctx = zstd.ZstdCompressor(level=1)
cobj = cctx.compressobj(size=len(b"foobar" * 256))
with_size = cobj.compress(b"foobar" * 256) + cobj.flush()
cctx = zstd.ZstdCompressor(level=1, write_content_size=False)
cobj = cctx.compressobj(size=len(b"foobar" * 256))
no_size = cobj.compress(b"foobar" * 256) + cobj.flush()
no_params = zstd.get_frame_parameters(no_size)
with_params = zstd.get_frame_parameters(with_size)
self.assertEqual(no_params.content_size, zstd.CONTENTSIZE_UNKNOWN)
self.assertEqual(with_params.content_size, 1536)
self.assertEqual(no_params.dict_id, 0)
self.assertEqual(with_params.dict_id, 0)
self.assertFalse(no_params.has_checksum)
self.assertFalse(with_params.has_checksum)
self.assertEqual(len(with_size), len(no_size) + 1)
def test_compress_after_finished(self):
cctx = zstd.ZstdCompressor()
cobj = cctx.compressobj()
cobj.compress(b"foo")
cobj.flush()
with self.assertRaisesRegex(
zstd.ZstdError, r"cannot call compress\(\) after compressor"
):
cobj.compress(b"foo")
with self.assertRaisesRegex(
zstd.ZstdError, "compressor object already finished"
):
cobj.flush()
def test_flush_block_repeated(self):
cctx = zstd.ZstdCompressor(level=1)
cobj = cctx.compressobj()
self.assertEqual(cobj.compress(b"foo"), b"")
self.assertEqual(
cobj.flush(zstd.COMPRESSOBJ_FLUSH_BLOCK),
b"\x28\xb5\x2f\xfd\x00\x48\x18\x00\x00foo",
)
self.assertEqual(cobj.compress(b"bar"), b"")
# 3 byte header plus content.
self.assertEqual(
cobj.flush(zstd.COMPRESSOBJ_FLUSH_BLOCK), b"\x18\x00\x00bar"
)
self.assertEqual(cobj.flush(), b"\x01\x00\x00")
def test_flush_empty_block(self):
cctx = zstd.ZstdCompressor(write_checksum=True)
cobj = cctx.compressobj()
cobj.compress(b"foobar")
cobj.flush(zstd.COMPRESSOBJ_FLUSH_BLOCK)
# No-op if no block is active (this is internal to zstd).
self.assertEqual(cobj.flush(zstd.COMPRESSOBJ_FLUSH_BLOCK), b"")
trailing = cobj.flush()
# 3 bytes block header + 4 bytes frame checksum
self.assertEqual(len(trailing), 7)
header = trailing[0:3]
self.assertEqual(header, b"\x01\x00\x00")
def test_multithreaded(self):
source = io.BytesIO()
source.write(b"a" * 1048576)
source.write(b"b" * 1048576)
source.write(b"c" * 1048576)
source.seek(0)
cctx = zstd.ZstdCompressor(level=1, threads=2)
cobj = cctx.compressobj()
chunks = []
while True:
d = source.read(8192)
if not d:
break
chunks.append(cobj.compress(d))
chunks.append(cobj.flush())
compressed = b"".join(chunks)
self.assertEqual(len(compressed), 119)
def test_frame_progression(self):
cctx = zstd.ZstdCompressor()
self.assertEqual(cctx.frame_progression(), (0, 0, 0))
cobj = cctx.compressobj()
cobj.compress(b"foobar")
self.assertEqual(cctx.frame_progression(), (6, 0, 0))
cobj.flush()
self.assertEqual(cctx.frame_progression(), (6, 6, 15))
def test_bad_size(self):
cctx = zstd.ZstdCompressor()
cobj = cctx.compressobj(size=2)
with self.assertRaisesRegex(zstd.ZstdError, "Src size is incorrect"):
cobj.compress(b"foo")
# Try another operation on this instance.
with self.assertRaisesRegex(zstd.ZstdError, "Src size is incorrect"):
cobj.compress(b"aa")
# Try another operation on the compressor.
cctx.compressobj(size=4)
cctx.compress(b"foobar")
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